Portola Weather Records (USC00047085)
Record envelope, standing records and threshold days for Portola (USC00047085), California, United States, with 112 years of record.
Key Facts for Portola
- Portola (USC00047085) is a weather station in California, United States at 39.81 latitude and -120.47 longitude, 1,478 m (4,850 ft) above sea level.
- The station reports from 1915 to 2026, 112 years of record.
- 1,464 records set at Portola still stand.
- Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
- Portola set a daily record high minimum temperature of 10.6 C (51.1 F) on 8 October 2026 (provisional).
Provisional Records
Records set in the last 60 days are provisional until they clear the revision window.
About the Station
- Location: California, United States, 39.81 latitude, -120.47 longitude.
- Elevation: 1,478 m (4,850 ft).
- Period of record: 1915 to 2026, 112 years.
- Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
13 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 20.0 C (68.0 F) | -31.1 C (-24.0 F) | 16.7 C (62.1 F) | -12.8 C (9.0 F) |
| Feb | 22.2 C (72.0 F) | -29.4 C (-20.9 F) | 17.2 C (63.0 F) | -13.3 C (8.1 F) |
| Mar | 28.9 C (84.0 F) | -24.4 C (-11.9 F) | 28.9 C (84.0 F) | -5.0 C (23.0 F) |
| Apr | 30.0 C (86.0 F) | -16.1 C (3.0 F) | 21.7 C (71.1 F) | -3.9 C (25.0 F) |
| May | 34.4 C (93.9 F) | -10.6 C (12.9 F) | 29.4 C (84.9 F) | -2.8 C (27.0 F) |
| Jun | 43.3 C (109.9 F) | -6.7 C (19.9 F) | 32.2 C (90.0 F) | 2.2 C (36.0 F) |
| Jul | 43.3 C (109.9 F) | -5.6 C (21.9 F) | 34.4 C (93.9 F) | 7.8 C (46.0 F) |
| Aug | 41.7 C (107.1 F) | -7.2 C (19.0 F) | 37.8 C (100.0 F) | 8.3 C (46.9 F) |
| Sep | 37.8 C (100.0 F) | -11.1 C (12.0 F) | 30.6 C (87.1 F) | 7.8 C (46.0 F) |
| Oct | 33.3 C (91.9 F) | -16.1 C (3.0 F) | 33.3 C (91.9 F) | 8.9 C (48.0 F) |
| Nov | 27.8 C (82.0 F) | -21.1 C (-6.0 F) | n/a | n/a |
| Dec | 22.2 C (72.0 F) | -33.3 C (-27.9 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1915 | 14 |
| 1916 | 49 |
| 1917 | 32 |
| 1918 | 28 |
| 1919 | 33 |
| 1920 | 35 |
| 1921 | 43 |
| 1922 | 25 |
| 1923 | 9 |
| 1924 | 54 |
| 1925 | 10 |
| 1926 | 17 |
| 1927 | 25 |
| 1928 | 22 |
| 1929 | 38 |
| 1930 | 7 |
| 1931 | 9 |
| 1932 | 31 |
| 1933 | 38 |
| 1934 | 8 |
| 1935 | 14 |
| 1936 | 17 |
| 1937 | 15 |
| 1938 | 13 |
| 1939 | 19 |
| 1940 | 6 |
| 1941 | 8 |
| 1942 | 8 |
| 1943 | 12 |
| 1944 | 6 |
| 1945 | 8 |
| 1946 | 5 |
| 1947 | 9 |
| 1948 | 9 |
| 1949 | 20 |
| 1950 | 18 |
| 1951 | 8 |
| 1952 | 15 |
| 1953 | 6 |
| 1954 | 13 |
| 1955 | 14 |
| 1956 | 16 |
| 1957 | 9 |
| 1958 | 18 |
| 1959 | 4 |
| 1960 | 8 |
| 1961 | 12 |
| 1962 | 13 |
| 1963 | 19 |
| 1964 | 10 |
| 1965 | 5 |
| 1966 | 16 |
| 1967 | 13 |
| 1968 | 4 |
| 1969 | 6 |
| 1970 | 3 |
| 1971 | 3 |
| 1972 | 8 |
| 1973 | 1 |
| 1974 | 9 |
| 1975 | 11 |
| 1976 | 20 |
| 1977 | 6 |
| 1978 | 11 |
| 1979 | 3 |
| 1980 | 14 |
| 1981 | 12 |
| 1982 | 2 |
| 1983 | 7 |
| 1984 | 9 |
| 1985 | 15 |
| 1986 | 20 |
| 1987 | 14 |
| 1988 | 6 |
| 1989 | 18 |
| 1990 | 25 |
| 1991 | 7 |
| 1992 | 9 |
| 1993 | 10 |
| 1994 | 7 |
| 1995 | 11 |
| 1996 | 11 |
| 1997 | 5 |
| 1998 | 11 |
| 1999 | 12 |
| 2000 | 7 |
| 2001 | 4 |
| 2002 | 10 |
| 2003 | 7 |
| 2004 | 11 |
| 2005 | 4 |
| 2006 | 6 |
| 2007 | 8 |
| 2008 | 7 |
| 2009 | 12 |
| 2010 | 12 |
| 2011 | 5 |
| 2012 | 11 |
| 2013 | 11 |
| 2014 | 7 |
| 2015 | 21 |
| 2016 | 15 |
| 2017 | 8 |
| 2018 | 4 |
| 2019 | 6 |
| 2020 | 6 |
| 2021 | 12 |
| 2022 | 8 |
| 2023 | 12 |
| 2024 | 11 |
| 2025 | 7 |
| 2026 | 9 |
All-Time Record Progression
4 new records| Date | Kind | Detail |
|---|---|---|
| 1955-12-19 | Record daily precipitation | Record daily precipitation 106.2 mm (4.2 in) |
| 1971-12-25 | Record daily snowfall | Record daily snowfall 102.1 cm (40.2 in) |
| 1972-12-09 | Record low minimum temperature | Record low minimum temperature -33.3 C (-27.9 F) |
| 2021-10-25 | Record daily precipitation | Record daily precipitation 144.0 mm (5.7 in) |
Wettest Day of Each Month
Oct: 144.0 mm (5.7 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 90.7 mm (3.6 in) | 21 January 1967 |
| Feb | 66.0 mm (2.6 in) | 10 February 2017 |
| Mar | 91.7 mm (3.6 in) | 10 March 1995 |
| Apr | 53.3 mm (2.1 in) | 8 April 2017 |
| May | 61.0 mm (2.4 in) | 16 May 1996 |
| Jun | 28.4 mm (1.1 in) | 1 June 1961 |
| Jul | 47.2 mm (1.9 in) | 11 July 2001 |
| Aug | 51.3 mm (2.0 in) | 20 August 1990 |
| Sep | 27.9 mm (1.1 in) | 11 September 1976 |
| Oct | 144.0 mm (5.7 in) | 25 October 2021 |
| Nov | 72.4 mm (2.9 in) | 17 November 1983 |
| Dec | 106.2 mm (4.2 in) | 19 December 1955 |
Period of Record Coverage
1915 to 2026| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1915 | 333 | 91% | Yes |
| 1916 | 365 | 100% | Yes |
| 1917 | 334 | 92% | Yes |
| 1918 | 365 | 100% | Yes |
| 1919 | 365 | 100% | Yes |
| 1920 | 336 | 92% | Yes |
| 1921 | 302 | 83% | No |
| 1922 | 354 | 97% | Yes |
| 1923 | 335 | 92% | Yes |
| 1924 | 353 | 96% | Yes |
| 1925 | 361 | 99% | Yes |
| 1926 | 229 | 63% | No |
| 1927 | 357 | 98% | Yes |
| 1928 | 364 | 99% | Yes |
| 1929 | 306 | 84% | No |
| 1930 | 365 | 100% | Yes |
| 1931 | 363 | 99% | Yes |
| 1932 | 334 | 91% | Yes |
| 1933 | 365 | 100% | Yes |
| 1934 | 304 | 83% | No |
| 1935 | 330 | 90% | Yes |
| 1936 | 356 | 97% | Yes |
| 1937 | 354 | 97% | Yes |
| 1938 | 364 | 100% | Yes |
| 1939 | 364 | 100% | Yes |
| 1940 | 366 | 100% | Yes |
| 1941 | 363 | 99% | Yes |
| 1942 | 353 | 97% | Yes |
| 1943 | 282 | 77% | No |
| 1944 | 288 | 79% | No |
| 1945 | 330 | 90% | Yes |
| 1946 | 360 | 99% | Yes |
| 1947 | 364 | 100% | Yes |
| 1948 | 363 | 99% | Yes |
| 1949 | 362 | 99% | Yes |
| 1950 | 363 | 99% | Yes |
| 1951 | 358 | 98% | Yes |
| 1952 | 366 | 100% | Yes |
| 1953 | 364 | 100% | Yes |
| 1954 | 363 | 99% | Yes |
| 1955 | 362 | 99% | Yes |
| 1956 | 362 | 99% | Yes |
| 1957 | 365 | 100% | Yes |
| 1958 | 334 | 92% | Yes |
| 1959 | 354 | 97% | Yes |
| 1960 | 345 | 94% | Yes |
| 1961 | 348 | 95% | Yes |
| 1962 | 365 | 100% | Yes |
| 1963 | 365 | 100% | Yes |
| 1964 | 332 | 91% | Yes |
| 1965 | 363 | 99% | Yes |
| 1966 | 363 | 99% | Yes |
| 1967 | 364 | 100% | Yes |
| 1968 | 331 | 90% | Yes |
| 1969 | 364 | 100% | Yes |
| 1970 | 316 | 87% | No |
| 1971 | 238 | 65% | No |
| 1972 | 271 | 74% | No |
| 1973 | 109 | 30% | No |
| 1974 | 237 | 65% | No |
| 1975 | 327 | 90% | No |
| 1976 | 329 | 90% | No |
| 1977 | 290 | 79% | No |
| 1978 | 316 | 87% | No |
| 1979 | 345 | 95% | Yes |
| 1980 | 333 | 91% | Yes |
| 1981 | 249 | 68% | No |
| 1982 | 304 | 83% | No |
| 1983 | 322 | 88% | No |
| 1984 | 309 | 84% | No |
| 1985 | 346 | 95% | Yes |
| 1986 | 360 | 99% | Yes |
| 1987 | 361 | 99% | Yes |
| 1988 | 359 | 98% | Yes |
| 1989 | 360 | 99% | Yes |
| 1990 | 355 | 97% | Yes |
| 1991 | 350 | 96% | Yes |
| 1992 | 341 | 93% | Yes |
| 1993 | 356 | 98% | Yes |
| 1994 | 358 | 98% | Yes |
| 1995 | 352 | 96% | Yes |
| 1996 | 342 | 93% | Yes |
| 1997 | 363 | 99% | Yes |
| 1998 | 347 | 95% | Yes |
| 1999 | 320 | 88% | No |
| 2000 | 354 | 97% | Yes |
| 2001 | 344 | 94% | Yes |
| 2002 | 362 | 99% | Yes |
| 2003 | 359 | 98% | Yes |
| 2004 | 355 | 97% | Yes |
| 2005 | 317 | 87% | No |
| 2006 | 340 | 93% | Yes |
| 2007 | 355 | 97% | Yes |
| 2008 | 351 | 96% | Yes |
| 2009 | 346 | 95% | Yes |
| 2010 | 341 | 93% | Yes |
| 2011 | 316 | 87% | No |
| 2012 | 293 | 80% | No |
| 2013 | 363 | 99% | Yes |
| 2014 | 363 | 99% | Yes |
| 2015 | 365 | 100% | Yes |
| 2016 | 364 | 99% | Yes |
| 2017 | 360 | 99% | Yes |
| 2018 | 340 | 93% | Yes |
| 2019 | 307 | 84% | No |
| 2020 | 351 | 96% | Yes |
| 2021 | 338 | 93% | Yes |
| 2022 | 189 | 52% | No |
| 2023 | 351 | 96% | Yes |
| 2024 | 351 | 96% | Yes |
| 2025 | 351 | 96% | Yes |
| 2026 | 187 | 51% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 8 October 2026 | Portola, US | daily high min (Provisional) | 10.6 C (51.1 F) | 2.3 C (4.1 F) | 69 years | 36 of 100 (Notable) |
| 8 October 2026 | Portola, US | daily high max (Provisional) | 32.8 C (91.0 F) | 2.2 C (4.0 F) | 45 years | 26 of 100 (Routine) |
| 7 October 2026 | Portola, US | daily high min (Provisional) | 10.6 C (51.1 F) | 1.7 C (3.1 F) | 80 years | 38 of 100 (Notable) |
| 7 October 2026 | Portola, US | daily high max (Provisional) | 32.2 C (90.0 F) | 1.1 C (2.0 F) | 45 years | 24 of 100 (Routine) |
| 6 October 2026 | Portola, US | daily high min (Provisional) | 10.6 C (51.1 F) | 0.6 C (1.1 F) | 65 years | 30 of 100 (Routine) |
| 6 October 2026 | Portola, US | daily high max (Tie, Provisional) | 31.1 C (88.0 F) | tie | 45 years | 5 of 100 (Routine) |
| 4 October 2026 | Portola, US | daily high min (Provisional) | 11.1 C (52.0 F) | 2.8 C (5.0 F) | 69 years | 37 of 100 (Notable) |
| 3 October 2026 | Portola, US | monthly high max (Tie, Provisional) | 33.3 C (91.9 F) | tie | 93 years | 11 of 100 (Routine) |
| 13 September 2026 | Portola, US | daily high min (Provisional) | 11.7 C (53.1 F) | 1.1 C (2.0 F) | 11 years | 16 of 100 (Routine) |
| 25 August 2026 | Portola, US | daily high min (Tie, Provisional) | 14.4 C (57.9 F) | tie | 108 years | 10 of 100 (Routine) |
| 24 August 2026 | Portola, US | daily high min (Provisional) | 17.2 C (63.0 F) | 1.6 C (2.9 F) | 108 years | 44 of 100 (Notable) |
| 5 August 2026 | Portola, US | daily high max (Tie) | 36.1 C (97.0 F) | tie | 48 years | 6 of 100 (Routine) |
| 26 May 2026 | Portola, US | daily high min | 8.9 C (48.0 F) | 0.6 C (1.1 F) | 56 years | 28 of 100 (Routine) |
| 25 May 2026 | Portola, US | daily high min | 12.2 C (54.0 F) | 2.8 C (5.0 F) | 27 years | 26 of 100 (Routine) |
| 24 May 2026 | Portola, US | monthly high min | 13.3 C (55.9 F) | 1.1 C (2.0 F) | 39 years | 34 of 100 (Routine) |
| 11 May 2026 | Portola, US | daily high max (Tie) | 29.4 C (84.9 F) | tie | 89 years | 9 of 100 (Routine) |
| 12 April 2026 | Portola, US | daily rain | 27.7 mm (1.1 in) | 9.4 mm (0.37 in) | 53 years | 39 of 100 (Notable) |
| 25 March 2026 | Portola, US | daily high max | 22.8 C (73.0 F) | 0.6 C (1.1 F) | 65 years | 30 of 100 (Routine) |
| 21 March 2026 | Portola, US | monthly high max | 28.9 C (84.0 F) | 1.7 C (3.1 F) | 0 years | 23 of 100 (Routine) |
| 20 March 2026 | Portola, US | monthly high max | 27.2 C (81.0 F) | 0.5 C (0.9 F) | 99 years | 49 of 100 (Notable) |
Climate Trend
77 complete years, 1916 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1916 | 6.6 C | -1.14 C |
| 1918 | 8.4 C | +0.62 C |
| 1919 | 7.8 C | +0.04 C |
| 1922 | 4.7 C | -3.04 C |
| 1924 | 6.5 C | -1.25 C |
| 1925 | 8.2 C | +0.42 C |
| 1927 | 5.8 C | -1.92 C |
| 1928 | 6.1 C | -1.60 C |
| 1930 | 6.7 C | -1.02 C |
| 1931 | 8.1 C | +0.40 C |
| 1933 | 6.2 C | -1.54 C |
| 1937 | 6.8 C | -0.89 C |
| 1938 | 7.1 C | -0.68 C |
| 1939 | 7.7 C | -0.02 C |
| 1940 | 8.2 C | +0.43 C |
| 1941 | 7.2 C | -0.52 C |
| 1942 | 6.8 C | -0.94 C |
| 1946 | 7.3 C | -0.41 C |
| 1947 | 7.9 C | +0.17 C |
| 1948 | 6.6 C | -1.12 C |
| 1949 | 7.0 C | -0.70 C |
| 1950 | 8.0 C | +0.24 C |
| 1951 | 7.8 C | +0.11 C |
| 1952 | 7.0 C | -0.74 C |
| 1953 | 7.9 C | +0.21 C |
| 1954 | 8.1 C | +0.35 C |
| 1955 | 6.9 C | -0.80 C |
| 1956 | 7.2 C | -0.50 C |
| 1957 | 7.4 C | -0.34 C |
| 1959 | 8.4 C | +0.70 C |
| 1960 | 7.6 C | -0.17 C |
| 1961 | 7.4 C | -0.29 C |
| 1962 | 7.7 C | -0.04 C |
| 1963 | 8.1 C | +0.37 C |
| 1965 | 7.3 C | -0.39 C |
| 1966 | 8.0 C | +0.22 C |
| 1967 | 7.9 C | +0.14 C |
| 1969 | 7.9 C | +0.16 C |
| 1975 | 6.9 C | -0.85 C |
| 1976 | 7.4 C | -0.37 C |
| 1979 | 8.2 C | +0.51 C |
| 1980 | 8.5 C | +0.75 C |
| 1982 | 7.4 C | -0.36 C |
| 1983 | 7.9 C | +0.20 C |
| 1985 | 7.3 C | -0.48 C |
| 1986 | 8.8 C | +1.06 C |
| 1987 | 8.3 C | +0.59 C |
| 1988 | 8.4 C | +0.68 C |
| 1989 | 7.2 C | -0.53 C |
| 1990 | 7.0 C | -0.70 C |
| 1991 | 7.9 C | +0.16 C |
| 1992 | 8.7 C | +1.00 C |
| 1993 | 6.8 C | -0.92 C |
| 1994 | 7.5 C | -0.21 C |
| 1995 | 8.0 C | +0.30 C |
| 1996 | 8.5 C | +0.75 C |
| 1997 | 8.1 C | +0.35 C |
| 1998 | 7.1 C | -0.65 C |
| 2000 | 8.1 C | +0.37 C |
| 2002 | 8.1 C | +0.38 C |
| 2003 | 8.5 C | +0.77 C |
| 2004 | 8.0 C | +0.22 C |
| 2006 | 8.0 C | +0.30 C |
| 2007 | 8.2 C | +0.44 C |
| 2008 | 7.8 C | +0.02 C |
| 2009 | 8.2 C | +0.45 C |
| 2010 | 7.7 C | +0.01 C |
| 2013 | 7.8 C | +0.08 C |
| 2014 | 9.7 C | +1.94 C |
| 2015 | 9.4 C | +1.64 C |
| 2016 | 8.9 C | +1.20 C |
| 2017 | 8.6 C | +0.91 C |
| 2018 | 8.7 C | +0.97 C |
| 2020 | 9.1 C | +1.38 C |
| 2023 | 7.7 C | -0.05 C |
| 2024 | 9.0 C | +1.31 C |
| 2025 | 9.4 C | +1.63 C |
The annual mean temperature here has risen by 0.2 C (0.1 to 0.2) per decade over 1916 to 2025. In Fahrenheit: 0.3 F (0.2 to 0.4) per decade. The slope is a straight line fitted to 77 complete years; the brackets give its 95 percent interval.
| Measure | Per decade (C) | Per decade (F) | Period | Complete years | Reading |
|---|---|---|---|---|---|
| Annual mean temperature | 0.2 C (0.1 to 0.2) per decade | 0.3 F (0.2 to 0.4) per decade | 1916 to 2025 | 77 | Rise |
| Mean daily maximum | 0.00 C (-0.08 to 0.08) per decade | -0.01 F (-0.15 to 0.14) per decade | 1916 to 2025 | 77 | Not clearly different from zero |
| Mean daily minimum | 0.3 C (0.3 to 0.4) per decade | 0.6 F (0.5 to 0.7) per decade | 1916 to 2025 | 77 | Rise |
A year is complete when all 12 months have at least 20 days of both daily maximum and daily minimum readings. The annual mean is the mean of the monthly means. The trend describes this one station over this period; it does not say what caused the change.
Extremes by Year
1915 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 43.3 C (109.9 F) | 1924 | 36.7 C (98.1 F) | 112 |
| Coldest night (TNn) | -33.3 C (-27.9 F) | 1972 | -20.0 C (-4.0 F) | 112 |
| Wettest day (Rx1day) | 144.0 mm (5.7 in) | 2021 | 44.6 mm (1.8 in) | 112 |
| Wettest five days (Rx5day) | 245.4 mm (9.7 in) | 1955 | 88.1 mm (3.5 in) | 112 |
| Longest dry spell (CDD) | 200 days | 1928 | 62 days | 112 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1915 | 36.7 C (98.1 F) |
| 1916 | 35.6 C (96.1 F) |
| 1917 | 36.7 C (98.1 F) |
| 1918 | 36.7 C (98.1 F) |
| 1919 | 37.2 C (99.0 F) |
| 1920 | 35.6 C (96.1 F) |
| 1921 | 36.7 C (98.1 F) |
| 1922 | 35.6 C (96.1 F) |
| 1923 | 35.6 C (96.1 F) |
| 1924 | 43.3 C (109.9 F) |
| 1925 | 36.7 C (98.1 F) |
| 1926 | 36.7 C (98.1 F) |
| 1927 | 36.7 C (98.1 F) |
| 1928 | 35.6 C (96.1 F) |
| 1929 | 38.3 C (100.9 F) |
| 1930 | 33.3 C (91.9 F) |
| 1931 | 40.0 C (104.0 F) |
| 1932 | 36.7 C (98.1 F) |
| 1933 | 36.1 C (97.0 F) |
| 1934 | 35.0 C (95.0 F) |
| 1935 | 37.8 C (100.0 F) |
| 1936 | 36.7 C (98.1 F) |
| 1937 | 37.2 C (99.0 F) |
| 1938 | 37.2 C (99.0 F) |
| 1939 | 37.8 C (100.0 F) |
| 1940 | 36.7 C (98.1 F) |
| 1941 | 35.6 C (96.1 F) |
| 1942 | 37.8 C (100.0 F) |
| 1943 | 35.0 C (95.0 F) |
| 1944 | 36.1 C (97.0 F) |
| 1945 | 37.2 C (99.0 F) |
| 1946 | 37.2 C (99.0 F) |
| 1947 | 34.4 C (93.9 F) |
| 1948 | 34.4 C (93.9 F) |
| 1949 | 34.4 C (93.9 F) |
| 1950 | 37.2 C (99.0 F) |
| 1951 | 35.0 C (95.0 F) |
| 1952 | 35.0 C (95.0 F) |
| 1953 | 35.0 C (95.0 F) |
| 1954 | 36.1 C (97.0 F) |
| 1955 | 37.8 C (100.0 F) |
| 1956 | 35.6 C (96.1 F) |
| 1957 | 35.0 C (95.0 F) |
| 1958 | 35.6 C (96.1 F) |
| 1959 | 37.2 C (99.0 F) |
| 1960 | 38.9 C (102.0 F) |
| 1961 | 38.3 C (100.9 F) |
| 1962 | 35.6 C (96.1 F) |
| 1963 | 33.3 C (91.9 F) |
| 1964 | 36.1 C (97.0 F) |
| 1965 | 33.3 C (91.9 F) |
| 1966 | 37.8 C (100.0 F) |
| 1967 | 34.4 C (93.9 F) |
| 1968 | 36.7 C (98.1 F) |
| 1969 | 35.0 C (95.0 F) |
| 1970 | 34.4 C (93.9 F) |
| 1971 | 36.7 C (98.1 F) |
| 1972 | 38.9 C (102.0 F) |
| 1973 | 34.4 C (93.9 F) |
| 1974 | 35.6 C (96.1 F) |
| 1975 | 36.7 C (98.1 F) |
| 1976 | 36.1 C (97.0 F) |
| 1977 | 37.8 C (100.0 F) |
| 1978 | 37.8 C (100.0 F) |
| 1979 | 37.8 C (100.0 F) |
| 1980 | 37.8 C (100.0 F) |
| 1981 | 41.7 C (107.1 F) |
| 1982 | 35.6 C (96.1 F) |
| 1983 | 37.8 C (100.0 F) |
| 1984 | 39.4 C (102.9 F) |
| 1985 | 35.6 C (96.1 F) |
| 1986 | 32.2 C (90.0 F) |
| 1987 | 34.4 C (93.9 F) |
| 1988 | 36.7 C (98.1 F) |
| 1989 | 36.1 C (97.0 F) |
| 1990 | 37.2 C (99.0 F) |
| 1991 | 35.6 C (96.1 F) |
| 1992 | 36.1 C (97.0 F) |
| 1993 | 36.7 C (98.1 F) |
| 1994 | 36.7 C (98.1 F) |
| 1995 | 32.8 C (91.0 F) |
| 1996 | 35.6 C (96.1 F) |
| 1997 | 36.7 C (98.1 F) |
| 1998 | 36.1 C (97.0 F) |
| 1999 | 32.8 C (91.0 F) |
| 2000 | 35.6 C (96.1 F) |
| 2001 | 35.6 C (96.1 F) |
| 2002 | 39.4 C (102.9 F) |
| 2003 | 37.8 C (100.0 F) |
| 2004 | 34.4 C (93.9 F) |
| 2005 | 35.0 C (95.0 F) |
| 2006 | 38.3 C (100.9 F) |
| 2007 | 38.3 C (100.9 F) |
| 2008 | 36.7 C (98.1 F) |
| 2009 | 35.6 C (96.1 F) |
| 2010 | 35.6 C (96.1 F) |
| 2011 | 35.0 C (95.0 F) |
| 2012 | 35.6 C (96.1 F) |
| 2013 | 37.2 C (99.0 F) |
| 2014 | 37.2 C (99.0 F) |
| 2015 | 36.1 C (97.0 F) |
| 2016 | 37.2 C (99.0 F) |
| 2017 | 37.8 C (100.0 F) |
| 2018 | 36.7 C (98.1 F) |
| 2019 | 35.6 C (96.1 F) |
| 2020 | 36.7 C (98.1 F) |
| 2021 | 37.8 C (100.0 F) |
| 2022 | 37.8 C (100.0 F) |
| 2023 | 38.3 C (100.9 F) |
| 2024 | 37.8 C (100.0 F) |
| 2025 | 36.7 C (98.1 F) |
| 2026 | 37.8 C (100.0 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1915 | -21.1 C (-6.0 F) |
| 1916 | -28.9 C (-20.0 F) |
| 1917 | -27.8 C (-18.0 F) |
| 1918 | -26.1 C (-15.0 F) |
| 1919 | -28.3 C (-18.9 F) |
| 1920 | -23.3 C (-9.9 F) |
| 1921 | -24.4 C (-11.9 F) |
| 1922 | -28.9 C (-20.0 F) |
| 1923 | -28.9 C (-20.0 F) |
| 1924 | -31.1 C (-24.0 F) |
| 1925 | -20.0 C (-4.0 F) |
| 1926 | -17.2 C (1.0 F) |
| 1927 | -20.6 C (-5.1 F) |
| 1928 | -20.6 C (-5.1 F) |
| 1929 | -17.8 C (0.0 F) |
| 1930 | -25.0 C (-13.0 F) |
| 1931 | -17.8 C (0.0 F) |
| 1932 | -27.8 C (-18.0 F) |
| 1933 | -28.9 C (-20.0 F) |
| 1934 | -18.9 C (-2.0 F) |
| 1935 | -22.8 C (-9.0 F) |
| 1936 | -17.2 C (1.0 F) |
| 1937 | -30.0 C (-22.0 F) |
| 1938 | -23.3 C (-9.9 F) |
| 1939 | -27.8 C (-18.0 F) |
| 1940 | -16.7 C (1.9 F) |
| 1941 | -16.1 C (3.0 F) |
| 1942 | -17.2 C (1.0 F) |
| 1943 | -16.1 C (3.0 F) |
| 1944 | -15.6 C (3.9 F) |
| 1945 | -17.2 C (1.0 F) |
| 1946 | -21.7 C (-7.1 F) |
| 1947 | -21.7 C (-7.1 F) |
| 1948 | -23.3 C (-9.9 F) |
| 1949 | -29.4 C (-20.9 F) |
| 1950 | -28.3 C (-18.9 F) |
| 1951 | -26.1 C (-15.0 F) |
| 1952 | -26.7 C (-16.1 F) |
| 1953 | -15.0 C (5.0 F) |
| 1954 | -16.1 C (3.0 F) |
| 1955 | -25.0 C (-13.0 F) |
| 1956 | -22.8 C (-9.0 F) |
| 1957 | -25.0 C (-13.0 F) |
| 1958 | -16.7 C (1.9 F) |
| 1959 | -22.8 C (-9.0 F) |
| 1960 | -24.4 C (-11.9 F) |
| 1961 | -16.1 C (3.0 F) |
| 1962 | -28.9 C (-20.0 F) |
| 1963 | -16.7 C (1.9 F) |
| 1964 | -16.7 C (1.9 F) |
| 1965 | -24.4 C (-11.9 F) |
| 1966 | -25.6 C (-14.1 F) |
| 1967 | -17.8 C (0.0 F) |
| 1968 | -24.4 C (-11.9 F) |
| 1969 | -22.8 C (-9.0 F) |
| 1970 | -18.9 C (-2.0 F) |
| 1971 | -30.0 C (-22.0 F) |
| 1972 | -33.3 C (-27.9 F) |
| 1973 | -18.9 C (-2.0 F) |
| 1974 | -20.0 C (-4.0 F) |
| 1975 | -18.3 C (-0.9 F) |
| 1976 | -17.2 C (1.0 F) |
| 1977 | -17.2 C (1.0 F) |
| 1978 | -20.6 C (-5.1 F) |
| 1979 | -22.8 C (-9.0 F) |
| 1980 | -14.4 C (6.1 F) |
| 1981 | -15.6 C (3.9 F) |
| 1982 | -17.8 C (0.0 F) |
| 1983 | -13.3 C (8.1 F) |
| 1984 | -21.1 C (-6.0 F) |
| 1985 | -17.8 C (0.0 F) |
| 1986 | -10.6 C (12.9 F) |
| 1987 | -21.7 C (-7.1 F) |
| 1988 | -23.9 C (-11.0 F) |
| 1989 | -27.8 C (-18.0 F) |
| 1990 | -30.6 C (-23.1 F) |
| 1991 | -15.6 C (3.9 F) |
| 1992 | -22.2 C (-8.0 F) |
| 1993 | -27.2 C (-17.0 F) |
| 1994 | -17.2 C (1.0 F) |
| 1995 | -15.6 C (3.9 F) |
| 1996 | -17.2 C (1.0 F) |
| 1997 | -18.9 C (-2.0 F) |
| 1998 | -22.2 C (-8.0 F) |
| 1999 | -14.4 C (6.1 F) |
| 2000 | -13.3 C (8.1 F) |
| 2001 | -19.4 C (-2.9 F) |
| 2002 | -21.7 C (-7.1 F) |
| 2003 | -17.8 C (0.0 F) |
| 2004 | -21.1 C (-6.0 F) |
| 2005 | -20.0 C (-4.0 F) |
| 2006 | -17.2 C (1.0 F) |
| 2007 | -18.3 C (-0.9 F) |
| 2008 | -22.2 C (-8.0 F) |
| 2009 | -25.6 C (-14.1 F) |
| 2010 | -20.0 C (-4.0 F) |
| 2011 | -22.8 C (-9.0 F) |
| 2012 | -20.0 C (-4.0 F) |
| 2013 | -25.6 C (-14.1 F) |
| 2014 | -12.2 C (10.0 F) |
| 2015 | -17.2 C (1.0 F) |
| 2016 | -18.3 C (-0.9 F) |
| 2017 | -18.9 C (-2.0 F) |
| 2018 | -19.4 C (-2.9 F) |
| 2019 | -14.4 C (6.1 F) |
| 2020 | -14.4 C (6.1 F) |
| 2021 | -16.1 C (3.0 F) |
| 2022 | -16.7 C (1.9 F) |
| 2023 | -18.9 C (-2.0 F) |
| 2024 | -17.2 C (1.0 F) |
| 2025 | -13.3 C (8.1 F) |
| 2026 | -13.3 C (8.1 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1915 | 61.0 mm (2.4 in) |
| 1916 | 38.1 mm (1.5 in) |
| 1917 | 35.6 mm (1.4 in) |
| 1918 | 38.1 mm (1.5 in) |
| 1919 | 40.6 mm (1.6 in) |
| 1920 | 38.1 mm (1.5 in) |
| 1921 | 38.1 mm (1.5 in) |
| 1922 | 50.8 mm (2.0 in) |
| 1923 | 38.1 mm (1.5 in) |
| 1924 | 25.7 mm (1.0 in) |
| 1925 | 27.2 mm (1.1 in) |
| 1926 | 50.8 mm (2.0 in) |
| 1927 | 40.6 mm (1.6 in) |
| 1928 | 27.9 mm (1.1 in) |
| 1929 | 52.3 mm (2.1 in) |
| 1930 | 30.5 mm (1.2 in) |
| 1931 | 38.1 mm (1.5 in) |
| 1932 | 45.7 mm (1.8 in) |
| 1933 | 30.5 mm (1.2 in) |
| 1934 | 36.8 mm (1.4 in) |
| 1935 | 37.1 mm (1.5 in) |
| 1936 | 59.7 mm (2.4 in) |
| 1937 | 66.0 mm (2.6 in) |
| 1938 | 51.1 mm (2.0 in) |
| 1939 | 50.8 mm (2.0 in) |
| 1940 | 44.5 mm (1.8 in) |
| 1941 | 61.7 mm (2.4 in) |
| 1942 | 55.9 mm (2.2 in) |
| 1943 | 23.6 mm (0.9 in) |
| 1944 | 53.6 mm (2.1 in) |
| 1945 | 50.8 mm (2.0 in) |
| 1946 | 61.0 mm (2.4 in) |
| 1947 | 48.5 mm (1.9 in) |
| 1948 | 38.1 mm (1.5 in) |
| 1949 | 32.8 mm (1.3 in) |
| 1950 | 63.5 mm (2.5 in) |
| 1951 | 52.8 mm (2.1 in) |
| 1952 | 58.4 mm (2.3 in) |
| 1953 | 38.1 mm (1.5 in) |
| 1954 | 43.2 mm (1.7 in) |
| 1955 | 106.2 mm (4.2 in) |
| 1956 | 38.1 mm (1.5 in) |
| 1957 | 37.1 mm (1.5 in) |
| 1958 | 32.3 mm (1.3 in) |
| 1959 | 41.9 mm (1.6 in) |
| 1960 | 41.7 mm (1.6 in) |
| 1961 | 34.5 mm (1.4 in) |
| 1962 | 98.8 mm (3.9 in) |
| 1963 | 44.7 mm (1.8 in) |
| 1964 | 58.9 mm (2.3 in) |
| 1965 | 48.8 mm (1.9 in) |
| 1966 | 41.1 mm (1.6 in) |
| 1967 | 90.7 mm (3.6 in) |
| 1968 | 28.4 mm (1.1 in) |
| 1969 | 66.0 mm (2.6 in) |
| 1970 | 58.4 mm (2.3 in) |
| 1971 | 54.4 mm (2.1 in) |
| 1972 | 28.2 mm (1.1 in) |
| 1973 | 15.2 mm (0.6 in) |
| 1974 | 54.1 mm (2.1 in) |
| 1975 | 39.4 mm (1.6 in) |
| 1976 | 28.7 mm (1.1 in) |
| 1977 | 44.7 mm (1.8 in) |
| 1978 | 34.3 mm (1.4 in) |
| 1979 | 37.3 mm (1.5 in) |
| 1980 | 55.9 mm (2.2 in) |
| 1981 | 50.8 mm (2.0 in) |
| 1982 | 63.5 mm (2.5 in) |
| 1983 | 72.4 mm (2.9 in) |
| 1984 | 27.9 mm (1.1 in) |
| 1985 | 59.4 mm (2.3 in) |
| 1986 | 57.2 mm (2.3 in) |
| 1987 | 35.1 mm (1.4 in) |
| 1988 | 62.5 mm (2.5 in) |
| 1989 | 44.5 mm (1.8 in) |
| 1990 | 51.3 mm (2.0 in) |
| 1991 | 42.2 mm (1.7 in) |
| 1992 | 91.4 mm (3.6 in) |
| 1993 | 52.6 mm (2.1 in) |
| 1994 | 34.3 mm (1.4 in) |
| 1995 | 91.7 mm (3.6 in) |
| 1996 | 61.0 mm (2.4 in) |
| 1997 | 67.8 mm (2.7 in) |
| 1998 | 38.9 mm (1.5 in) |
| 1999 | 64.8 mm (2.6 in) |
| 2000 | 47.2 mm (1.9 in) |
| 2001 | 47.2 mm (1.9 in) |
| 2002 | 47.0 mm (1.9 in) |
| 2003 | 39.4 mm (1.6 in) |
| 2004 | 48.8 mm (1.9 in) |
| 2005 | 40.6 mm (1.6 in) |
| 2006 | 34.3 mm (1.4 in) |
| 2007 | 38.1 mm (1.5 in) |
| 2008 | 64.3 mm (2.5 in) |
| 2009 | 46.0 mm (1.8 in) |
| 2010 | 47.0 mm (1.9 in) |
| 2011 | 51.3 mm (2.0 in) |
| 2012 | 44.5 mm (1.8 in) |
| 2013 | 15.2 mm (0.6 in) |
| 2014 | 41.9 mm (1.6 in) |
| 2015 | 43.2 mm (1.7 in) |
| 2016 | 38.9 mm (1.5 in) |
| 2017 | 66.0 mm (2.6 in) |
| 2018 | 37.6 mm (1.5 in) |
| 2019 | 34.8 mm (1.4 in) |
| 2020 | 43.9 mm (1.7 in) |
| 2021 | 144.0 mm (5.7 in) |
| 2022 | 63.5 mm (2.5 in) |
| 2023 | 69.1 mm (2.7 in) |
| 2024 | 43.2 mm (1.7 in) |
| 2025 | 54.6 mm (2.1 in) |
| 2026 | 44.5 mm (1.8 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1915 | 61.0 mm (2.4 in) |
| 1916 | 61.0 mm (2.4 in) |
| 1917 | 55.7 mm (2.2 in) |
| 1918 | 63.5 mm (2.5 in) |
| 1919 | 96.5 mm (3.8 in) |
| 1920 | 40.2 mm (1.6 in) |
| 1921 | 91.5 mm (3.6 in) |
| 1922 | 132.1 mm (5.2 in) |
| 1923 | 20.4 mm (0.8 in) |
| 1924 | 36.1 mm (1.4 in) |
| 1925 | 57.1 mm (2.2 in) |
| 1926 | 134.6 mm (5.3 in) |
| 1927 | 88.8 mm (3.5 in) |
| 1928 | 104.0 mm (4.1 in) |
| 1929 | 189.0 mm (7.4 in) |
| 1930 | 68.6 mm (2.7 in) |
| 1931 | 53.4 mm (2.1 in) |
| 1932 | 76.2 mm (3.0 in) |
| 1933 | 78.8 mm (3.1 in) |
| 1934 | 63.2 mm (2.5 in) |
| 1935 | 87.4 mm (3.4 in) |
| 1936 | 94.1 mm (3.7 in) |
| 1937 | 118.1 mm (4.6 in) |
| 1938 | 99.1 mm (3.9 in) |
| 1939 | 58.4 mm (2.3 in) |
| 1940 | 117.0 mm (4.6 in) |
| 1941 | 65.5 mm (2.6 in) |
| 1942 | 108.2 mm (4.3 in) |
| 1943 | 26.6 mm (1.0 in) |
| 1944 | 75.5 mm (3.0 in) |
| 1945 | 136.2 mm (5.4 in) |
| 1946 | 115.4 mm (4.5 in) |
| 1947 | 54.1 mm (2.1 in) |
| 1948 | 43.2 mm (1.7 in) |
| 1949 | 58.7 mm (2.3 in) |
| 1950 | 129.4 mm (5.1 in) |
| 1951 | 151.8 mm (6.0 in) |
| 1952 | 126.6 mm (5.0 in) |
| 1953 | 72.9 mm (2.9 in) |
| 1954 | 71.4 mm (2.8 in) |
| 1955 | 245.4 mm (9.7 in) |
| 1956 | 66.8 mm (2.6 in) |
| 1957 | 116.1 mm (4.6 in) |
| 1958 | 93.7 mm (3.7 in) |
| 1959 | 78.0 mm (3.1 in) |
| 1960 | 80.5 mm (3.2 in) |
| 1961 | 70.6 mm (2.8 in) |
| 1962 | 244.8 mm (9.6 in) |
| 1963 | 122.6 mm (4.8 in) |
| 1964 | 142.7 mm (5.6 in) |
| 1965 | 103.0 mm (4.1 in) |
| 1966 | 95.4 mm (3.8 in) |
| 1967 | 156.7 mm (6.2 in) |
| 1968 | 63.1 mm (2.5 in) |
| 1969 | 168.6 mm (6.6 in) |
| 1970 | 116.9 mm (4.6 in) |
| 1971 | 94.5 mm (3.7 in) |
| 1972 | 40.4 mm (1.6 in) |
| 1973 | 21.6 mm (0.9 in) |
| 1974 | 91.9 mm (3.6 in) |
| 1975 | 67.3 mm (2.6 in) |
| 1976 | 50.7 mm (2.0 in) |
| 1977 | 44.7 mm (1.8 in) |
| 1978 | 91.7 mm (3.6 in) |
| 1979 | 90.7 mm (3.6 in) |
| 1980 | 148.1 mm (5.8 in) |
| 1981 | 101.4 mm (4.0 in) |
| 1982 | 104.2 mm (4.1 in) |
| 1983 | 108.3 mm (4.3 in) |
| 1984 | 55.5 mm (2.2 in) |
| 1985 | 75.4 mm (3.0 in) |
| 1986 | 224.6 mm (8.8 in) |
| 1987 | 48.8 mm (1.9 in) |
| 1988 | 85.3 mm (3.4 in) |
| 1989 | 69.1 mm (2.7 in) |
| 1990 | 68.8 mm (2.7 in) |
| 1991 | 131.0 mm (5.2 in) |
| 1992 | 156.4 mm (6.2 in) |
| 1993 | 220.9 mm (8.7 in) |
| 1994 | 52.1 mm (2.1 in) |
| 1995 | 174.5 mm (6.9 in) |
| 1996 | 119.6 mm (4.7 in) |
| 1997 | 175.9 mm (6.9 in) |
| 1998 | 66.4 mm (2.6 in) |
| 1999 | 125.7 mm (4.9 in) |
| 2000 | 91.5 mm (3.6 in) |
| 2001 | 68.1 mm (2.7 in) |
| 2002 | 145.8 mm (5.7 in) |
| 2003 | 66.4 mm (2.6 in) |
| 2004 | 77.8 mm (3.1 in) |
| 2005 | 80.5 mm (3.2 in) |
| 2006 | 79.8 mm (3.1 in) |
| 2007 | 87.4 mm (3.4 in) |
| 2008 | 96.6 mm (3.8 in) |
| 2009 | 96.5 mm (3.8 in) |
| 2010 | 91.0 mm (3.6 in) |
| 2011 | 69.4 mm (2.7 in) |
| 2012 | 142.0 mm (5.6 in) |
| 2013 | 18.0 mm (0.7 in) |
| 2014 | 83.9 mm (3.3 in) |
| 2015 | 76.5 mm (3.0 in) |
| 2016 | 77.9 mm (3.1 in) |
| 2017 | 223.1 mm (8.8 in) |
| 2018 | 100.3 mm (3.9 in) |
| 2019 | 56.6 mm (2.2 in) |
| 2020 | 47.2 mm (1.9 in) |
| 2021 | 183.4 mm (7.2 in) |
| 2022 | 66.0 mm (2.6 in) |
| 2023 | 104.9 mm (4.1 in) |
| 2024 | 141.5 mm (5.6 in) |
| 2025 | 166.4 mm (6.6 in) |
| 2026 | 78.5 mm (3.1 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1915 | 77 days |
| 1916 | 43 days |
| 1917 | 43 days |
| 1918 | 25 days |
| 1919 | 37 days |
| 1920 | 18 days |
| 1921 | 11 days |
| 1922 | 62 days |
| 1923 | 18 days |
| 1924 | 47 days |
| 1925 | 57 days |
| 1926 | 30 days |
| 1927 | 77 days |
| 1928 | 200 days |
| 1929 | 99 days |
| 1930 | 62 days |
| 1931 | 95 days |
| 1932 | 38 days |
| 1933 | 74 days |
| 1934 | 62 days |
| 1935 | 124 days |
| 1936 | 89 days |
| 1937 | 85 days |
| 1938 | 62 days |
| 1939 | 68 days |
| 1940 | 31 days |
| 1941 | 30 days |
| 1942 | 136 days |
| 1943 | 71 days |
| 1944 | 76 days |
| 1945 | 93 days |
| 1946 | 67 days |
| 1947 | 66 days |
| 1948 | 96 days |
| 1949 | 82 days |
| 1950 | 33 days |
| 1951 | 94 days |
| 1952 | 41 days |
| 1953 | 42 days |
| 1954 | 70 days |
| 1955 | 67 days |
| 1956 | 73 days |
| 1957 | 98 days |
| 1958 | 40 days |
| 1959 | 84 days |
| 1960 | 57 days |
| 1961 | 46 days |
| 1962 | 48 days |
| 1963 | 46 days |
| 1964 | 58 days |
| 1965 | 38 days |
| 1966 | 48 days |
| 1967 | 41 days |
| 1968 | 68 days |
| 1969 | 110 days |
| 1970 | 60 days |
| 1971 | 36 days |
| 1972 | 80 days |
| 1973 | 42 days |
| 1974 | 57 days |
| 1975 | 54 days |
| 1976 | 37 days |
| 1977 | 35 days |
| 1978 | 59 days |
| 1979 | 39 days |
| 1980 | 69 days |
| 1981 | 92 days |
| 1982 | 38 days |
| 1983 | 62 days |
| 1984 | 37 days |
| 1985 | 47 days |
| 1986 | 55 days |
| 1987 | 85 days |
| 1988 | 86 days |
| 1989 | 59 days |
| 1990 | 47 days |
| 1991 | 41 days |
| 1992 | 45 days |
| 1993 | 69 days |
| 1994 | 98 days |
| 1995 | 129 days |
| 1996 | 33 days |
| 1997 | 48 days |
| 1998 | 60 days |
| 1999 | 35 days |
| 2000 | 85 days |
| 2001 | 80 days |
| 2002 | 110 days |
| 2003 | 69 days |
| 2004 | 94 days |
| 2005 | 83 days |
| 2006 | 98 days |
| 2007 | 108 days |
| 2008 | 125 days |
| 2009 | 66 days |
| 2010 | 35 days |
| 2011 | 5 days |
| 2012 | 89 days |
| 2013 | 48 days |
| 2014 | 60 days |
| 2015 | 53 days |
| 2016 | 106 days |
| 2017 | 77 days |
| 2018 | 109 days |
| 2019 | 88 days |
| 2020 | 91 days |
| 2021 | 41 days |
| 2022 | 41 days |
| 2023 | 53 days |
| 2024 | 53 days |
| 2025 | 98 days |
| 2026 | 89 days |
Each chart shows one value per year; the dot marks the record year. TXx is the hottest daily maximum, TNn the coldest daily minimum, Rx1day and Rx5day the largest one-day and five-day rain totals, and CDD the longest run of days with less than 1 mm of rain. A year with missing days can understate an extreme.
Frost Dates and Growing Season
77 years with a frostAcross 77 years with a frost, the median last spring frost at Portola falls on 20 June and the median first autumn frost on 1 August, which leaves a median of 39 days between them.
In 1988 to 2025 the median growing season was 94 days. That is 78 days more than in 1916 to 1959.
Fitted over all years, the growing season changes by +9.4 days per decade at this station.
| Measure | Median, all years | Earliest period (1916 to 1959) | Recent period (1988 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 20 June | 26 June | 13 June | 13 days earlier | -1.8 days per decade |
| First autumn frost | 1 August | 8 July | 14 September | 68 days later | +7.6 days per decade |
| Growing days | 39 days | 16 days | 94 days | 78 days more | +9.4 days per decade |
A frost day is a day with a daily minimum at or below 0 C (32 F). The last spring frost and the first autumn frost are the last and first such days of the cold season, and growing days are the days between them. A negative trend for the last spring frost means it comes earlier.
Rainfall Return Levels
83 years, 1927 to 2025A day with at least 46.1 mm (1.8 in) of rain is expected about once in 2 years. A day with at least 121.8 mm (4.8 in) of rain is expected about once in 100 years.
| Expected about once in | A day with at least | Note |
|---|---|---|
| 2 years | 46.1 mm (1.8 in) | |
| 5 years | 61.8 mm (2.4 in) | |
| 10 years | 73.9 mm (2.9 in) | |
| 25 years | 91.2 mm (3.6 in) | |
| 50 years | 105.7 mm (4.2 in) | |
| 100 years | 121.8 mm (4.8 in) | Longer than the 83 years of record |
The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 83 years of values from 1927 to 2025.
A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.
The largest wettest-day totals in the fit: 144.0 mm (5.7 in) in 2021; 106.2 mm (4.2 in) in 1955; 98.8 mm (3.9 in) in 1962.
Station Changes
1 suspectedOne change was suspected in the annual mean temperature of Portola, at 2002. Each is measured against neighbouring stations.
- Relative to 5 neighbouring stations, the station's annual mean temperature from 2002 ran 0.3 C (0.6 F) lower than in the years before (likely change).
| Year | Shift (C) | Shift (F) | Strength | Neighbours |
|---|---|---|---|---|
| 2002 | -0.3 | -0.6 | likely | 5 |
Possible change at the station (a move, a new instrument or a new site); the record is kept as measured. A "likely" change has a larger test statistic than a "possible" one. Neither says why the station differs from its neighbours. How changes are found, and the largest ones.
Climate Twins
2006 to 2025 against 1961 to 1990Over 2006 to 2025, Portola had a mean temperature of 8.6 C (47.4 F) and 562.1 mm (22.1 in) of rain a year. The 3 stations whose 1961 to 1990 climate was closest to that are Heber (Black Mesa) Rs (United States, 1,064 km away), Pullman 2 NW (United States, 818 km away) and Ft Bidwell (United States, 231 km away).
| Twin station | Country | Distance away | Mean temperature, 1961-1990 | Rain a year, 1961-1990 | Climate difference |
|---|---|---|---|---|---|
| Heber (Black Mesa) Rs | United States | 1,064 km (661 mi) | 9.1 C (48.3 F) | 475.0 mm (18.7 in) | 0.76 |
| Pullman 2 NW | United States | 818 km (508 mi) | 8.3 C (47.0 F) | 536.0 mm (21.1 in) | 0.76 |
| Ft Bidwell | United States | 231 km (144 mi) | 8.9 C (47.9 F) | 436.5 mm (17.2 in) | 0.82 |
Twins are stations, not cities. A twin is one of the three stations at least 100 km away whose earlier climate is closest to this station's recent one, so a close match does not mean the two places look alike in other ways. A station move or a gap in a record can change that station's averages. The list describes past climate; it is not a forecast and does not say what caused any change. How twins are found, and a search for any station.
Download the Data
Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-14 (14 October 2026). Records are computed by this site and are not official.
Data as of . Last revised (2026-10-14).