Mtn Dell Dam Weather Records (USC00425892)
Record envelope, standing records and threshold days for Mtn Dell Dam (USC00425892), Utah, United States, with 107 years of record.
Key Facts for Mtn Dell Dam
- Mtn Dell Dam (USC00425892) is a weather station in Utah, United States at 40.75 latitude and -111.72 longitude, 1,652 m (5,420 ft) above sea level.
- The station reports from 1920 to 2026, 107 years of record.
- 1,464 records set at Mtn Dell Dam still stand.
- Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
- Mtn Dell Dam set a daily record high minimum temperature of 13.9 C (57.0 F) on 10 October 2026 (provisional).
Provisional Records
Records set in the last 60 days are provisional until they clear the revision window.
About the Station
- Location: Utah, United States, 40.75 latitude, -111.72 longitude.
- Elevation: 1,652 m (5,420 ft).
- Period of record: 1920 to 2026, 107 years.
- Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
23 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 17.8 C (64.0 F) | -34.4 C (-29.9 F) | 10.6 C (51.1 F) | -16.1 C (3.0 F) |
| Feb | 21.1 C (70.0 F) | -29.4 C (-20.9 F) | 14.4 C (57.9 F) | -16.1 C (3.0 F) |
| Mar | 28.3 C (82.9 F) | -25.6 C (-14.1 F) | 28.3 C (82.9 F) | -10.0 C (14.0 F) |
| Apr | 29.4 C (84.9 F) | -15.6 C (3.9 F) | 24.4 C (75.9 F) | -8.9 C (16.0 F) |
| May | 33.3 C (91.9 F) | -10.0 C (14.0 F) | 31.7 C (89.1 F) | -2.8 C (27.0 F) |
| Jun | 37.8 C (100.0 F) | -6.1 C (21.0 F) | 33.3 C (91.9 F) | -0.6 C (30.9 F) |
| Jul | 38.9 C (102.0 F) | 1.1 C (34.0 F) | 38.3 C (100.9 F) | 5.0 C (41.0 F) |
| Aug | 38.9 C (102.0 F) | -3.9 C (25.0 F) | 37.8 C (100.0 F) | 5.6 C (42.1 F) |
| Sep | 36.7 C (98.1 F) | -8.9 C (16.0 F) | 30.6 C (87.1 F) | 1.7 C (35.1 F) |
| Oct | 31.1 C (88.0 F) | -13.9 C (7.0 F) | 28.9 C (84.0 F) | 3.3 C (37.9 F) |
| Nov | 23.3 C (73.9 F) | -26.7 C (-16.1 F) | n/a | n/a |
| Dec | 17.2 C (63.0 F) | -31.7 C (-25.1 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1927 | 2 |
| 1935 | 2 |
| 1936 | 12 |
| 1937 | 31 |
| 1938 | 6 |
| 1940 | 8 |
| 1941 | 31 |
| 1942 | 19 |
| 1943 | 13 |
| 1944 | 18 |
| 1945 | 18 |
| 1946 | 16 |
| 1947 | 16 |
| 1948 | 26 |
| 1949 | 27 |
| 1950 | 30 |
| 1951 | 20 |
| 1952 | 24 |
| 1953 | 16 |
| 1954 | 36 |
| 1955 | 33 |
| 1956 | 13 |
| 1957 | 8 |
| 1958 | 24 |
| 1959 | 18 |
| 1960 | 45 |
| 1961 | 30 |
| 1962 | 40 |
| 1963 | 26 |
| 1964 | 28 |
| 1965 | 29 |
| 1966 | 28 |
| 1967 | 22 |
| 1968 | 14 |
| 1969 | 17 |
| 1970 | 20 |
| 1971 | 21 |
| 1972 | 17 |
| 1973 | 12 |
| 1974 | 9 |
| 1975 | 17 |
| 1976 | 17 |
| 1977 | 13 |
| 1978 | 19 |
| 1979 | 13 |
| 1980 | 7 |
| 1981 | 9 |
| 1982 | 17 |
| 1983 | 5 |
| 1984 | 12 |
| 1985 | 16 |
| 1986 | 13 |
| 1987 | 8 |
| 1988 | 12 |
| 1989 | 22 |
| 1990 | 18 |
| 1996 | 20 |
| 1997 | 7 |
| 1998 | 14 |
| 1999 | 12 |
| 2000 | 11 |
| 2001 | 14 |
| 2002 | 8 |
| 2003 | 25 |
| 2004 | 10 |
| 2005 | 6 |
| 2006 | 10 |
| 2007 | 12 |
| 2008 | 4 |
| 2009 | 10 |
| 2010 | 10 |
| 2011 | 6 |
| 2012 | 13 |
| 2013 | 19 |
| 2014 | 11 |
| 2015 | 26 |
| 2016 | 21 |
| 2017 | 25 |
| 2018 | 11 |
| 2019 | 11 |
| 2020 | 19 |
| 2021 | 12 |
| 2022 | 21 |
| 2023 | 11 |
| 2024 | 8 |
| 2025 | 17 |
| 2026 | 17 |
All-Time Record Progression
4 new records| Date | Kind | Detail |
|---|---|---|
| 1972-12-10 | Record low maximum temperature | Record low maximum temperature -14.4 C (6.1 F) |
| 1985-12-08 | Record daily snowfall | Record daily snowfall 71.1 cm (28.0 in) |
| 2004-09-21 | Record daily precipitation | Record daily precipitation 127.3 mm (5.0 in) |
| 2012-06-26 | Record high minimum temperature | Record high minimum temperature 23.3 C (73.9 F) |
Wettest Day of Each Month
Sep: 127.3 mm (5.0 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 42.9 mm (1.7 in) | 14 January 1953 |
| Feb | 50.0 mm (2.0 in) | 7 February 1950 |
| Mar | 38.1 mm (1.5 in) | 26 March 1920 |
| Apr | 53.6 mm (2.1 in) | 23 April 1957 |
| May | 55.9 mm (2.2 in) | 17 May 2015 |
| Jun | 59.4 mm (2.3 in) | 6 June 2007 |
| Jul | 45.0 mm (1.8 in) | 2 July 1925 |
| Aug | 48.5 mm (1.9 in) | 2 August 2021 |
| Sep | 127.3 mm (5.0 in) | 21 September 2004 |
| Oct | 54.9 mm (2.2 in) | 7 October 1985 |
| Nov | 41.7 mm (1.6 in) | 26 November 1970 |
| Dec | 52.1 mm (2.1 in) | 23 December 1964 |
Period of Record Coverage
1927 to 2026| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1927 | 3 | 1% | No |
| 1935 | 60 | 16% | No |
| 1936 | 142 | 39% | No |
| 1937 | 89 | 24% | No |
| 1938 | 60 | 16% | No |
| 1940 | 139 | 38% | No |
| 1941 | 360 | 99% | Yes |
| 1942 | 365 | 100% | Yes |
| 1943 | 359 | 98% | Yes |
| 1944 | 358 | 98% | Yes |
| 1945 | 354 | 97% | Yes |
| 1946 | 360 | 99% | Yes |
| 1947 | 338 | 93% | Yes |
| 1948 | 349 | 95% | Yes |
| 1949 | 365 | 100% | Yes |
| 1950 | 362 | 99% | Yes |
| 1951 | 362 | 99% | Yes |
| 1952 | 366 | 100% | Yes |
| 1953 | 365 | 100% | Yes |
| 1954 | 364 | 100% | Yes |
| 1955 | 361 | 99% | Yes |
| 1956 | 362 | 99% | Yes |
| 1957 | 358 | 98% | Yes |
| 1958 | 361 | 99% | Yes |
| 1959 | 359 | 98% | Yes |
| 1960 | 360 | 98% | Yes |
| 1961 | 359 | 98% | Yes |
| 1962 | 362 | 99% | Yes |
| 1963 | 363 | 99% | Yes |
| 1964 | 305 | 83% | No |
| 1965 | 333 | 91% | Yes |
| 1966 | 363 | 99% | Yes |
| 1967 | 364 | 100% | Yes |
| 1968 | 364 | 99% | Yes |
| 1969 | 362 | 99% | Yes |
| 1970 | 359 | 98% | Yes |
| 1971 | 357 | 98% | Yes |
| 1972 | 364 | 99% | Yes |
| 1973 | 334 | 92% | Yes |
| 1974 | 364 | 100% | Yes |
| 1975 | 357 | 98% | Yes |
| 1976 | 366 | 100% | Yes |
| 1977 | 364 | 100% | Yes |
| 1978 | 365 | 100% | Yes |
| 1979 | 327 | 90% | No |
| 1980 | 365 | 100% | Yes |
| 1981 | 364 | 100% | Yes |
| 1982 | 364 | 100% | Yes |
| 1983 | 361 | 99% | Yes |
| 1984 | 362 | 99% | Yes |
| 1985 | 364 | 100% | Yes |
| 1986 | 361 | 99% | Yes |
| 1987 | 361 | 99% | Yes |
| 1988 | 362 | 99% | Yes |
| 1989 | 364 | 100% | Yes |
| 1990 | 315 | 86% | No |
| 1991 | 78 | 21% | No |
| 1996 | 361 | 99% | Yes |
| 1997 | 348 | 95% | Yes |
| 1998 | 330 | 90% | Yes |
| 1999 | 358 | 98% | Yes |
| 2000 | 358 | 98% | Yes |
| 2001 | 358 | 98% | Yes |
| 2002 | 328 | 90% | No |
| 2003 | 358 | 98% | Yes |
| 2004 | 344 | 94% | Yes |
| 2005 | 356 | 98% | Yes |
| 2006 | 355 | 97% | Yes |
| 2007 | 313 | 86% | No |
| 2008 | 331 | 90% | Yes |
| 2009 | 354 | 97% | Yes |
| 2010 | 331 | 91% | Yes |
| 2011 | 360 | 99% | Yes |
| 2012 | 334 | 91% | Yes |
| 2013 | 365 | 100% | Yes |
| 2014 | 363 | 99% | Yes |
| 2015 | 365 | 100% | Yes |
| 2016 | 366 | 100% | Yes |
| 2017 | 362 | 99% | Yes |
| 2018 | 364 | 100% | Yes |
| 2019 | 323 | 88% | No |
| 2020 | 352 | 96% | Yes |
| 2021 | 362 | 99% | Yes |
| 2022 | 364 | 100% | Yes |
| 2023 | 364 | 100% | Yes |
| 2024 | 365 | 100% | Yes |
| 2025 | 365 | 100% | Yes |
| 2026 | 283 | 78% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 10 October 2026 | Mtn Dell Dam, US | daily high min (Provisional) | 13.9 C (57.0 F) | 4.5 C (8.1 F) | 23 years | 26 of 100 (Routine) |
| 8 October 2026 | Mtn Dell Dam, US | daily high min (Provisional) | 12.2 C (54.0 F) | 1.6 C (2.9 F) | 79 years | 36 of 100 (Notable) |
| 6 October 2026 | Mtn Dell Dam, US | daily high max (Provisional) | 28.9 C (84.0 F) | 1.1 C (2.0 F) | 69 years | 31 of 100 (Routine) |
| 17 September 2026 | Mtn Dell Dam, US | daily high min (Provisional) | 16.7 C (62.1 F) | 2.3 C (4.1 F) | 25 years | 21 of 100 (Routine) |
| 13 September 2026 | Mtn Dell Dam, US | daily high min (Provisional) | 16.1 C (61.0 F) | 2.8 C (5.0 F) | 89 years | 41 of 100 (Notable) |
| 28 August 2026 | Mtn Dell Dam, US | daily high min (Provisional) | 16.7 C (62.1 F) | 1.7 C (3.1 F) | 84 years | 39 of 100 (Notable) |
| 22 August 2026 | Mtn Dell Dam, US | daily high max (Provisional) | 35.0 C (95.0 F) | 0.6 C (1.1 F) | 64 years | 30 of 100 (Routine) |
| 21 August 2026 | Mtn Dell Dam, US | daily high max (Tie, Provisional) | 36.1 C (97.0 F) | tie | 65 years | 7 of 100 (Routine) |
| 12 August 2026 | Mtn Dell Dam, US | daily high min | 17.2 C (63.0 F) | 1.1 C (2.0 F) | 11 years | 15 of 100 (Routine) |
| 8 August 2026 | Mtn Dell Dam, US | daily high max | 36.7 C (98.1 F) | 1.1 C (2.0 F) | 60 years | 31 of 100 (Routine) |
| 7 August 2026 | Mtn Dell Dam, US | daily high max (Tie) | 36.1 C (97.0 F) | tie | 7 years | 3 of 100 (Routine) |
| 5 August 2026 | Mtn Dell Dam, US | daily low min (Tie) | 5.6 C (42.1 F) | tie | 64 years | 7 of 100 (Routine) |
| 1 August 2026 | Mtn Dell Dam, US | daily high max (Tie) | 37.2 C (99.0 F) | tie | 5 years | 2 of 100 (Routine) |
| 31 July 2026 | Mtn Dell Dam, US | daily high max (Tie) | 36.1 C (97.0 F) | tie | 5 years | 2 of 100 (Routine) |
| 29 July 2026 | Mtn Dell Dam, US | daily high min | 18.3 C (64.9 F) | 1.6 C (2.9 F) | 80 years | 38 of 100 (Notable) |
| 27 July 2026 | Mtn Dell Dam, US | daily high min | 21.1 C (70.0 F) | 2.2 C (4.0 F) | 28 years | 24 of 100 (Routine) |
| 13 July 2026 | Mtn Dell Dam, US | daily high max (Tie) | 38.3 C (100.9 F) | tie | 24 years | 4 of 100 (Routine) |
| 12 July 2026 | Mtn Dell Dam, US | daily high max | 37.8 C (100.0 F) | 0.6 C (1.1 F) | 1 year | 12 of 100 (Routine) |
| 9 June 2026 | Mtn Dell Dam, US | daily high min | 14.4 C (57.9 F) | 1.1 C (2.0 F) | 9 years | 14 of 100 (Routine) |
| 27 May 2026 | Mtn Dell Dam, US | daily high min | 13.3 C (55.9 F) | 0.5 C (0.9 F) | 89 years | 36 of 100 (Notable) |
Climate Trend
66 complete years, 1941 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1941 | 7.9 C | -0.55 C |
| 1942 | 6.7 C | -1.71 C |
| 1944 | 7.3 C | -1.16 C |
| 1945 | 7.7 C | -0.71 C |
| 1946 | 8.9 C | +0.46 C |
| 1947 | 7.9 C | -0.53 C |
| 1948 | 7.5 C | -0.92 C |
| 1949 | 7.5 C | -0.97 C |
| 1950 | 8.3 C | -0.15 C |
| 1951 | 7.3 C | -1.16 C |
| 1952 | 7.5 C | -0.93 C |
| 1953 | 8.4 C | -0.09 C |
| 1954 | 8.8 C | +0.38 C |
| 1955 | 7.3 C | -1.16 C |
| 1956 | 8.4 C | -0.05 C |
| 1957 | 8.4 C | -0.07 C |
| 1958 | 9.2 C | +0.79 C |
| 1959 | 8.7 C | +0.21 C |
| 1960 | 8.8 C | +0.33 C |
| 1961 | 8.6 C | +0.15 C |
| 1962 | 8.3 C | -0.14 C |
| 1963 | 8.4 C | -0.03 C |
| 1966 | 7.9 C | -0.58 C |
| 1967 | 7.9 C | -0.55 C |
| 1968 | 7.8 C | -0.70 C |
| 1969 | 8.3 C | -0.20 C |
| 1970 | 7.8 C | -0.63 C |
| 1971 | 7.4 C | -1.02 C |
| 1972 | 7.9 C | -0.54 C |
| 1974 | 8.4 C | -0.05 C |
| 1975 | 7.1 C | -1.33 C |
| 1976 | 7.7 C | -0.72 C |
| 1977 | 8.4 C | -0.03 C |
| 1978 | 8.4 C | -0.10 C |
| 1980 | 8.5 C | +0.09 C |
| 1981 | 9.3 C | +0.80 C |
| 1982 | 7.3 C | -1.14 C |
| 1983 | 8.3 C | -0.11 C |
| 1984 | 6.9 C | -1.58 C |
| 1985 | 7.4 C | -1.02 C |
| 1986 | 9.0 C | +0.56 C |
| 1987 | 8.8 C | +0.37 C |
| 1988 | 9.0 C | +0.50 C |
| 1989 | 8.6 C | +0.18 C |
| 1996 | 9.2 C | +0.76 C |
| 1997 | 8.6 C | +0.17 C |
| 1999 | 8.9 C | +0.45 C |
| 2000 | 9.2 C | +0.74 C |
| 2001 | 9.2 C | +0.73 C |
| 2003 | 9.7 C | +1.20 C |
| 2004 | 8.5 C | 0.00 C |
| 2005 | 9.0 C | +0.59 C |
| 2006 | 8.8 C | +0.35 C |
| 2009 | 8.3 C | -0.13 C |
| 2011 | 8.0 C | -0.42 C |
| 2013 | 8.1 C | -0.38 C |
| 2014 | 9.7 C | +1.29 C |
| 2016 | 11.1 C | +2.64 C |
| 2017 | 11.1 C | +2.62 C |
| 2018 | 11.1 C | +2.62 C |
| 2020 | 9.0 C | +0.51 C |
| 2021 | 9.4 C | +0.95 C |
| 2022 | 8.1 C | -0.35 C |
| 2023 | 8.1 C | -0.36 C |
| 2024 | 9.3 C | +0.89 C |
| 2025 | 9.7 C | +1.24 C |
The annual mean temperature here has risen by 0.2 C (0.1 to 0.3) per decade over 1941 to 2025. In Fahrenheit: 0.4 F (0.2 to 0.5) per decade. The slope is a straight line fitted to 66 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 0.3) per decade | 0.4 F (0.2 to 0.5) per decade | 1941 to 2025 | 66 | Rise |
| Mean daily maximum | 0.12 C (0.03 to 0.22) per decade | 0.2 F (0.1 to 0.4) per decade | 1941 to 2025 | 66 | Rise |
| Mean daily minimum | 0.3 C (0.2 to 0.4) per decade | 0.5 F (0.4 to 0.7) per decade | 1941 to 2025 | 66 | 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
1920 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 38.9 C (102.0 F) | 1960 | 35.6 C (96.1 F) | 88 |
| Coldest night (TNn) | -34.4 C (-29.9 F) | 1963 | -22.2 C (-8.0 F) | 87 |
| Wettest day (Rx1day) | 127.3 mm (5.0 in) | 2004 | 35.6 mm (1.4 in) | 102 |
| Wettest five days (Rx5day) | 143.3 mm (5.6 in) | 2004 | 58.9 mm (2.3 in) | 102 |
| Longest dry spell (CDD) | 81 days | 1944 | 32 days | 102 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1920 | n/a |
| 1921 | n/a |
| 1922 | n/a |
| 1923 | n/a |
| 1924 | n/a |
| 1925 | n/a |
| 1926 | n/a |
| 1927 | 21.7 C (71.1 F) |
| 1928 | n/a |
| 1929 | n/a |
| 1930 | n/a |
| 1931 | n/a |
| 1932 | n/a |
| 1933 | n/a |
| 1934 | n/a |
| 1935 | 28.9 C (84.0 F) |
| 1936 | 33.3 C (91.9 F) |
| 1937 | 33.3 C (91.9 F) |
| 1938 | 35.0 C (95.0 F) |
| 1939 | n/a |
| 1940 | 35.6 C (96.1 F) |
| 1941 | 32.8 C (91.0 F) |
| 1942 | 33.3 C (91.9 F) |
| 1943 | 34.4 C (93.9 F) |
| 1944 | 33.9 C (93.0 F) |
| 1945 | 33.3 C (91.9 F) |
| 1946 | 35.0 C (95.0 F) |
| 1947 | 32.2 C (90.0 F) |
| 1948 | 34.4 C (93.9 F) |
| 1949 | 35.0 C (95.0 F) |
| 1950 | 34.4 C (93.9 F) |
| 1951 | 33.9 C (93.0 F) |
| 1952 | 32.8 C (91.0 F) |
| 1953 | 33.3 C (91.9 F) |
| 1954 | 36.1 C (97.0 F) |
| 1955 | 34.4 C (93.9 F) |
| 1956 | 33.9 C (93.0 F) |
| 1957 | 35.0 C (95.0 F) |
| 1958 | 35.0 C (95.0 F) |
| 1959 | 35.0 C (95.0 F) |
| 1960 | 38.9 C (102.0 F) |
| 1961 | 37.8 C (100.0 F) |
| 1962 | 38.9 C (102.0 F) |
| 1963 | 37.2 C (99.0 F) |
| 1964 | 36.7 C (98.1 F) |
| 1965 | 34.4 C (93.9 F) |
| 1966 | 37.2 C (99.0 F) |
| 1967 | 35.0 C (95.0 F) |
| 1968 | 35.0 C (95.0 F) |
| 1969 | 38.3 C (100.9 F) |
| 1970 | 36.1 C (97.0 F) |
| 1971 | 35.6 C (96.1 F) |
| 1972 | 36.1 C (97.0 F) |
| 1973 | 35.6 C (96.1 F) |
| 1974 | 35.6 C (96.1 F) |
| 1975 | 33.9 C (93.0 F) |
| 1976 | 36.1 C (97.0 F) |
| 1977 | 35.0 C (95.0 F) |
| 1978 | 36.1 C (97.0 F) |
| 1979 | 36.7 C (98.1 F) |
| 1980 | 36.1 C (97.0 F) |
| 1981 | 36.1 C (97.0 F) |
| 1982 | 35.6 C (96.1 F) |
| 1983 | 35.0 C (95.0 F) |
| 1984 | 34.4 C (93.9 F) |
| 1985 | 36.1 C (97.0 F) |
| 1986 | 34.4 C (93.9 F) |
| 1987 | 35.0 C (95.0 F) |
| 1988 | 36.7 C (98.1 F) |
| 1989 | 36.7 C (98.1 F) |
| 1990 | 35.6 C (96.1 F) |
| 1991 | 26.7 C (80.1 F) |
| 1996 | 35.6 C (96.1 F) |
| 1997 | 36.1 C (97.0 F) |
| 1998 | 36.1 C (97.0 F) |
| 1999 | 33.9 C (93.0 F) |
| 2000 | 36.1 C (97.0 F) |
| 2001 | 36.7 C (98.1 F) |
| 2002 | 38.3 C (100.9 F) |
| 2003 | 36.7 C (98.1 F) |
| 2004 | 33.9 C (93.0 F) |
| 2005 | 36.1 C (97.0 F) |
| 2006 | 36.1 C (97.0 F) |
| 2007 | 36.1 C (97.0 F) |
| 2008 | 35.0 C (95.0 F) |
| 2009 | 37.2 C (99.0 F) |
| 2010 | 35.0 C (95.0 F) |
| 2011 | 35.0 C (95.0 F) |
| 2012 | 35.6 C (96.1 F) |
| 2013 | 36.1 C (97.0 F) |
| 2014 | 36.1 C (97.0 F) |
| 2015 | 36.7 C (98.1 F) |
| 2016 | 35.6 C (96.1 F) |
| 2017 | 35.6 C (96.1 F) |
| 2018 | 36.1 C (97.0 F) |
| 2019 | 36.1 C (97.0 F) |
| 2020 | 37.2 C (99.0 F) |
| 2021 | 36.1 C (97.0 F) |
| 2022 | 36.7 C (98.1 F) |
| 2023 | 36.1 C (97.0 F) |
| 2024 | 37.2 C (99.0 F) |
| 2025 | 35.6 C (96.1 F) |
| 2026 | 38.3 C (100.9 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1920 | n/a |
| 1921 | n/a |
| 1922 | n/a |
| 1923 | n/a |
| 1924 | n/a |
| 1925 | n/a |
| 1926 | n/a |
| 1927 | n/a |
| 1928 | n/a |
| 1929 | n/a |
| 1930 | n/a |
| 1931 | n/a |
| 1932 | n/a |
| 1933 | n/a |
| 1934 | n/a |
| 1935 | -15.0 C (5.0 F) |
| 1936 | -16.7 C (1.9 F) |
| 1937 | -28.9 C (-20.0 F) |
| 1938 | -18.9 C (-2.0 F) |
| 1939 | n/a |
| 1940 | -19.4 C (-2.9 F) |
| 1941 | -19.4 C (-2.9 F) |
| 1942 | -29.4 C (-20.9 F) |
| 1943 | -21.7 C (-7.1 F) |
| 1944 | -20.0 C (-4.0 F) |
| 1945 | -22.8 C (-9.0 F) |
| 1946 | -21.1 C (-6.0 F) |
| 1947 | -26.1 C (-15.0 F) |
| 1948 | -23.3 C (-9.9 F) |
| 1949 | -27.8 C (-18.0 F) |
| 1950 | -27.8 C (-18.0 F) |
| 1951 | -27.8 C (-18.0 F) |
| 1952 | -26.1 C (-15.0 F) |
| 1953 | -20.6 C (-5.1 F) |
| 1954 | -23.9 C (-11.0 F) |
| 1955 | -26.7 C (-16.1 F) |
| 1956 | -22.8 C (-9.0 F) |
| 1957 | -23.9 C (-11.0 F) |
| 1958 | -19.4 C (-2.9 F) |
| 1959 | -21.7 C (-7.1 F) |
| 1960 | -25.0 C (-13.0 F) |
| 1961 | -25.6 C (-14.1 F) |
| 1962 | -28.3 C (-18.9 F) |
| 1963 | -34.4 C (-29.9 F) |
| 1964 | -26.7 C (-16.1 F) |
| 1965 | -22.2 C (-8.0 F) |
| 1966 | -25.6 C (-14.1 F) |
| 1967 | -23.3 C (-9.9 F) |
| 1968 | -22.2 C (-8.0 F) |
| 1969 | -20.0 C (-4.0 F) |
| 1970 | -22.8 C (-9.0 F) |
| 1971 | -28.3 C (-18.9 F) |
| 1972 | -27.8 C (-18.0 F) |
| 1973 | -26.1 C (-15.0 F) |
| 1974 | -22.8 C (-9.0 F) |
| 1975 | -23.9 C (-11.0 F) |
| 1976 | -23.3 C (-9.9 F) |
| 1977 | -25.6 C (-14.1 F) |
| 1978 | -23.9 C (-11.0 F) |
| 1979 | -26.7 C (-16.1 F) |
| 1980 | -22.2 C (-8.0 F) |
| 1981 | -18.3 C (-0.9 F) |
| 1982 | -29.4 C (-20.9 F) |
| 1983 | -21.7 C (-7.1 F) |
| 1984 | -29.4 C (-20.9 F) |
| 1985 | -29.4 C (-20.9 F) |
| 1986 | -17.8 C (0.0 F) |
| 1987 | -21.1 C (-6.0 F) |
| 1988 | -25.0 C (-13.0 F) |
| 1989 | -27.2 C (-17.0 F) |
| 1990 | -31.7 C (-25.1 F) |
| 1991 | -22.2 C (-8.0 F) |
| 1996 | -23.3 C (-9.9 F) |
| 1997 | -18.9 C (-2.0 F) |
| 1998 | -22.2 C (-8.0 F) |
| 1999 | -20.0 C (-4.0 F) |
| 2000 | -17.2 C (1.0 F) |
| 2001 | -20.0 C (-4.0 F) |
| 2002 | -26.1 C (-15.0 F) |
| 2003 | -18.3 C (-0.9 F) |
| 2004 | -20.0 C (-4.0 F) |
| 2005 | -19.4 C (-2.9 F) |
| 2006 | -19.4 C (-2.9 F) |
| 2007 | -21.7 C (-7.1 F) |
| 2008 | -21.7 C (-7.1 F) |
| 2009 | -23.3 C (-9.9 F) |
| 2010 | -19.4 C (-2.9 F) |
| 2011 | -22.2 C (-8.0 F) |
| 2012 | -20.6 C (-5.1 F) |
| 2013 | -28.9 C (-20.0 F) |
| 2014 | -19.4 C (-2.9 F) |
| 2015 | -17.2 C (1.0 F) |
| 2016 | -15.6 C (3.9 F) |
| 2017 | -16.7 C (1.9 F) |
| 2018 | -13.3 C (8.1 F) |
| 2019 | -13.3 C (8.1 F) |
| 2020 | -17.8 C (0.0 F) |
| 2021 | -19.4 C (-2.9 F) |
| 2022 | -22.8 C (-9.0 F) |
| 2023 | -27.2 C (-17.0 F) |
| 2024 | -17.8 C (0.0 F) |
| 2025 | -21.7 C (-7.1 F) |
| 2026 | -16.1 C (3.0 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1920 | 38.1 mm (1.5 in) |
| 1921 | 27.2 mm (1.1 in) |
| 1922 | 24.4 mm (1.0 in) |
| 1923 | 25.7 mm (1.0 in) |
| 1924 | 17.8 mm (0.7 in) |
| 1925 | 45.0 mm (1.8 in) |
| 1926 | 61.5 mm (2.4 in) |
| 1927 | 31.8 mm (1.3 in) |
| 1928 | 21.6 mm (0.9 in) |
| 1929 | 40.6 mm (1.6 in) |
| 1930 | 55.9 mm (2.2 in) |
| 1931 | 36.8 mm (1.4 in) |
| 1932 | 21.3 mm (0.8 in) |
| 1933 | 23.9 mm (0.9 in) |
| 1934 | 22.4 mm (0.9 in) |
| 1935 | 44.5 mm (1.8 in) |
| 1936 | 30.0 mm (1.2 in) |
| 1937 | 52.1 mm (2.1 in) |
| 1938 | 31.0 mm (1.2 in) |
| 1939 | 23.4 mm (0.9 in) |
| 1940 | 31.5 mm (1.2 in) |
| 1941 | 34.0 mm (1.3 in) |
| 1942 | 38.9 mm (1.5 in) |
| 1943 | 51.3 mm (2.0 in) |
| 1944 | 48.3 mm (1.9 in) |
| 1945 | 34.5 mm (1.4 in) |
| 1946 | 37.6 mm (1.5 in) |
| 1947 | 33.5 mm (1.3 in) |
| 1948 | 35.3 mm (1.4 in) |
| 1949 | 32.5 mm (1.3 in) |
| 1950 | 50.0 mm (2.0 in) |
| 1951 | 39.4 mm (1.6 in) |
| 1952 | 26.7 mm (1.1 in) |
| 1953 | 42.9 mm (1.7 in) |
| 1954 | 25.9 mm (1.0 in) |
| 1955 | 31.0 mm (1.2 in) |
| 1956 | 37.3 mm (1.5 in) |
| 1957 | 53.6 mm (2.1 in) |
| 1958 | 38.9 mm (1.5 in) |
| 1959 | 23.9 mm (0.9 in) |
| 1960 | 26.7 mm (1.1 in) |
| 1961 | 33.8 mm (1.3 in) |
| 1962 | 30.5 mm (1.2 in) |
| 1963 | 33.8 mm (1.3 in) |
| 1964 | 52.1 mm (2.1 in) |
| 1965 | 34.3 mm (1.4 in) |
| 1966 | 25.9 mm (1.0 in) |
| 1967 | 28.7 mm (1.1 in) |
| 1968 | 50.8 mm (2.0 in) |
| 1969 | 42.9 mm (1.7 in) |
| 1970 | 41.7 mm (1.6 in) |
| 1971 | 23.4 mm (0.9 in) |
| 1972 | 47.0 mm (1.9 in) |
| 1973 | 27.9 mm (1.1 in) |
| 1974 | 23.9 mm (0.9 in) |
| 1975 | 38.9 mm (1.5 in) |
| 1976 | 19.6 mm (0.8 in) |
| 1977 | 47.0 mm (1.9 in) |
| 1978 | 61.2 mm (2.4 in) |
| 1979 | 37.8 mm (1.5 in) |
| 1980 | 26.4 mm (1.0 in) |
| 1981 | 29.2 mm (1.1 in) |
| 1982 | 46.7 mm (1.8 in) |
| 1983 | 29.0 mm (1.1 in) |
| 1984 | 41.4 mm (1.6 in) |
| 1985 | 54.9 mm (2.2 in) |
| 1986 | 35.8 mm (1.4 in) |
| 1987 | 29.2 mm (1.1 in) |
| 1988 | 32.5 mm (1.3 in) |
| 1989 | 34.5 mm (1.4 in) |
| 1990 | 18.5 mm (0.7 in) |
| 1991 | n/a |
| 1996 | 41.7 mm (1.6 in) |
| 1997 | 34.0 mm (1.3 in) |
| 1998 | 49.5 mm (1.9 in) |
| 1999 | 47.5 mm (1.9 in) |
| 2000 | 30.0 mm (1.2 in) |
| 2001 | 40.4 mm (1.6 in) |
| 2002 | 28.4 mm (1.1 in) |
| 2003 | 32.5 mm (1.3 in) |
| 2004 | 127.3 mm (5.0 in) |
| 2005 | 41.9 mm (1.6 in) |
| 2006 | 34.5 mm (1.4 in) |
| 2007 | 59.4 mm (2.3 in) |
| 2008 | 36.8 mm (1.4 in) |
| 2009 | 38.1 mm (1.5 in) |
| 2010 | 43.9 mm (1.7 in) |
| 2011 | 32.5 mm (1.3 in) |
| 2012 | 37.1 mm (1.5 in) |
| 2013 | 26.2 mm (1.0 in) |
| 2014 | 30.2 mm (1.2 in) |
| 2015 | 55.9 mm (2.2 in) |
| 2016 | 37.1 mm (1.5 in) |
| 2017 | 39.4 mm (1.6 in) |
| 2018 | 41.4 mm (1.6 in) |
| 2019 | 36.8 mm (1.4 in) |
| 2020 | 38.9 mm (1.5 in) |
| 2021 | 48.5 mm (1.9 in) |
| 2022 | 40.6 mm (1.6 in) |
| 2023 | 28.7 mm (1.1 in) |
| 2024 | 32.5 mm (1.3 in) |
| 2025 | 49.5 mm (1.9 in) |
| 2026 | 26.7 mm (1.1 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1920 | 53.8 mm (2.1 in) |
| 1921 | 46.7 mm (1.8 in) |
| 1922 | 37.6 mm (1.5 in) |
| 1923 | 38.2 mm (1.5 in) |
| 1924 | 33.2 mm (1.3 in) |
| 1925 | 60.0 mm (2.4 in) |
| 1926 | 75.5 mm (3.0 in) |
| 1927 | 62.0 mm (2.4 in) |
| 1928 | 52.0 mm (2.0 in) |
| 1929 | 61.3 mm (2.4 in) |
| 1930 | 91.0 mm (3.6 in) |
| 1931 | 38.8 mm (1.5 in) |
| 1932 | 55.1 mm (2.2 in) |
| 1933 | 46.8 mm (1.8 in) |
| 1934 | 47.4 mm (1.9 in) |
| 1935 | 53.4 mm (2.1 in) |
| 1936 | 62.5 mm (2.5 in) |
| 1937 | 76.7 mm (3.0 in) |
| 1938 | 73.2 mm (2.9 in) |
| 1939 | 33.5 mm (1.3 in) |
| 1940 | 54.5 mm (2.1 in) |
| 1941 | 44.1 mm (1.7 in) |
| 1942 | 66.6 mm (2.6 in) |
| 1943 | 70.5 mm (2.8 in) |
| 1944 | 79.9 mm (3.1 in) |
| 1945 | 51.3 mm (2.0 in) |
| 1946 | 80.1 mm (3.2 in) |
| 1947 | 65.7 mm (2.6 in) |
| 1948 | 41.4 mm (1.6 in) |
| 1949 | 74.1 mm (2.9 in) |
| 1950 | 66.0 mm (2.6 in) |
| 1951 | 55.4 mm (2.2 in) |
| 1952 | 42.9 mm (1.7 in) |
| 1953 | 75.1 mm (3.0 in) |
| 1954 | 33.6 mm (1.3 in) |
| 1955 | 49.3 mm (1.9 in) |
| 1956 | 59.5 mm (2.3 in) |
| 1957 | 77.6 mm (3.1 in) |
| 1958 | 53.5 mm (2.1 in) |
| 1959 | 48.0 mm (1.9 in) |
| 1960 | 41.7 mm (1.6 in) |
| 1961 | 37.3 mm (1.5 in) |
| 1962 | 46.2 mm (1.8 in) |
| 1963 | 57.9 mm (2.3 in) |
| 1964 | 138.5 mm (5.5 in) |
| 1965 | 63.0 mm (2.5 in) |
| 1966 | 46.0 mm (1.8 in) |
| 1967 | 52.8 mm (2.1 in) |
| 1968 | 67.8 mm (2.7 in) |
| 1969 | 74.4 mm (2.9 in) |
| 1970 | 60.5 mm (2.4 in) |
| 1971 | 37.6 mm (1.5 in) |
| 1972 | 60.0 mm (2.4 in) |
| 1973 | 66.3 mm (2.6 in) |
| 1974 | 51.3 mm (2.0 in) |
| 1975 | 76.8 mm (3.0 in) |
| 1976 | 43.2 mm (1.7 in) |
| 1977 | 60.5 mm (2.4 in) |
| 1978 | 72.2 mm (2.8 in) |
| 1979 | 57.4 mm (2.3 in) |
| 1980 | 62.3 mm (2.5 in) |
| 1981 | 50.0 mm (2.0 in) |
| 1982 | 138.6 mm (5.5 in) |
| 1983 | 62.2 mm (2.4 in) |
| 1984 | 87.1 mm (3.4 in) |
| 1985 | 73.7 mm (2.9 in) |
| 1986 | 73.8 mm (2.9 in) |
| 1987 | 52.7 mm (2.1 in) |
| 1988 | 55.4 mm (2.2 in) |
| 1989 | 49.8 mm (2.0 in) |
| 1990 | 27.5 mm (1.1 in) |
| 1991 | n/a |
| 1996 | 55.6 mm (2.2 in) |
| 1997 | 64.2 mm (2.5 in) |
| 1998 | 73.7 mm (2.9 in) |
| 1999 | 71.1 mm (2.8 in) |
| 2000 | 45.4 mm (1.8 in) |
| 2001 | 101.1 mm (4.0 in) |
| 2002 | 53.3 mm (2.1 in) |
| 2003 | 79.8 mm (3.1 in) |
| 2004 | 143.3 mm (5.6 in) |
| 2005 | 55.6 mm (2.2 in) |
| 2006 | 56.7 mm (2.2 in) |
| 2007 | 72.6 mm (2.9 in) |
| 2008 | 53.3 mm (2.1 in) |
| 2009 | 49.8 mm (2.0 in) |
| 2010 | 93.4 mm (3.7 in) |
| 2011 | 62.1 mm (2.4 in) |
| 2012 | 58.2 mm (2.3 in) |
| 2013 | 43.3 mm (1.7 in) |
| 2014 | 60.5 mm (2.4 in) |
| 2015 | 79.6 mm (3.1 in) |
| 2016 | 75.2 mm (3.0 in) |
| 2017 | 50.0 mm (2.0 in) |
| 2018 | 67.9 mm (2.7 in) |
| 2019 | 68.1 mm (2.7 in) |
| 2020 | 48.8 mm (1.9 in) |
| 2021 | 88.9 mm (3.5 in) |
| 2022 | 57.9 mm (2.3 in) |
| 2023 | 57.9 mm (2.3 in) |
| 2024 | 60.1 mm (2.4 in) |
| 2025 | 63.2 mm (2.5 in) |
| 2026 | 41.5 mm (1.6 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1920 | 15 days |
| 1921 | 24 days |
| 1922 | 21 days |
| 1923 | 22 days |
| 1924 | 33 days |
| 1925 | 19 days |
| 1926 | 47 days |
| 1927 | 26 days |
| 1928 | 42 days |
| 1929 | 36 days |
| 1930 | 21 days |
| 1931 | 47 days |
| 1932 | 37 days |
| 1933 | 40 days |
| 1934 | 30 days |
| 1935 | 73 days |
| 1936 | 31 days |
| 1937 | 22 days |
| 1938 | 33 days |
| 1939 | 20 days |
| 1940 | 34 days |
| 1941 | 37 days |
| 1942 | 30 days |
| 1943 | 52 days |
| 1944 | 81 days |
| 1945 | 32 days |
| 1946 | 55 days |
| 1947 | 40 days |
| 1948 | 40 days |
| 1949 | 49 days |
| 1950 | 28 days |
| 1951 | 24 days |
| 1952 | 64 days |
| 1953 | 50 days |
| 1954 | 20 days |
| 1955 | 38 days |
| 1956 | 41 days |
| 1957 | 20 days |
| 1958 | 63 days |
| 1959 | 45 days |
| 1960 | 33 days |
| 1961 | 31 days |
| 1962 | 28 days |
| 1963 | 51 days |
| 1964 | 38 days |
| 1965 | 18 days |
| 1966 | 23 days |
| 1967 | 42 days |
| 1968 | 39 days |
| 1969 | 30 days |
| 1970 | 22 days |
| 1971 | 22 days |
| 1972 | 61 days |
| 1973 | 27 days |
| 1974 | 76 days |
| 1975 | 35 days |
| 1976 | 34 days |
| 1977 | 25 days |
| 1978 | 55 days |
| 1979 | 58 days |
| 1980 | 28 days |
| 1981 | 25 days |
| 1982 | 20 days |
| 1983 | 25 days |
| 1984 | 25 days |
| 1985 | 29 days |
| 1986 | 26 days |
| 1987 | 31 days |
| 1988 | 37 days |
| 1989 | 26 days |
| 1990 | 37 days |
| 1991 | n/a |
| 1996 | 28 days |
| 1997 | 23 days |
| 1998 | 22 days |
| 1999 | 36 days |
| 2000 | 39 days |
| 2001 | 32 days |
| 2002 | 25 days |
| 2003 | 29 days |
| 2004 | 19 days |
| 2005 | 35 days |
| 2006 | 25 days |
| 2007 | 47 days |
| 2008 | 40 days |
| 2009 | 29 days |
| 2010 | 38 days |
| 2011 | 40 days |
| 2012 | 16 days |
| 2013 | 34 days |
| 2014 | 32 days |
| 2015 | 23 days |
| 2016 | 42 days |
| 2017 | 33 days |
| 2018 | 43 days |
| 2019 | 26 days |
| 2020 | 42 days |
| 2021 | 28 days |
| 2022 | 24 days |
| 2023 | 29 days |
| 2024 | 29 days |
| 2025 | 46 days |
| 2026 | 25 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
66 years with a frostAcross 66 years with a frost, the median last spring frost at Mtn Dell Dam falls on 23 May and the median first autumn frost on 22 September, which leaves a median of 121 days between them.
In 1982 to 2025 the median growing season was 133 days. That is 22 days more than in 1941 to 1974.
Fitted over all years, the growing season changes by +4.6 days per decade at this station.
| Measure | Median, all years | Earliest period (1941 to 1974) | Recent period (1982 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 23 May | 31 May | 21 May | 10 days earlier | -2.0 days per decade |
| First autumn frost | 22 September | 17 September | 28 September | 11 days later | +2.6 days per decade |
| Growing days | 121 days | 111 days | 133 days | 22 days more | +4.6 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
90 years, 1923 to 2025A day with at least 35.8 mm (1.4 in) of rain is expected about once in 2 years. A day with at least 78.7 mm (3.1 in) of rain is expected about once in 100 years.
| Expected about once in | A day with at least | Note |
|---|---|---|
| 2 years | 35.8 mm (1.4 in) | |
| 5 years | 46.6 mm (1.8 in) | |
| 10 years | 54.1 mm (2.1 in) | |
| 25 years | 63.7 mm (2.5 in) | |
| 50 years | 71.2 mm (2.8 in) | |
| 100 years | 78.7 mm (3.1 in) | Longer than the 90 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, 90 years of values from 1923 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: 127.3 mm (5.0 in) in 2004; 61.5 mm (2.4 in) in 1926; 61.2 mm (2.4 in) in 1978.
Station Changes
1 suspectedOne change was suspected in the annual mean temperature of Mtn Dell Dam, at 2021. Each is measured against neighbouring stations.
- Relative to 5 neighbouring stations, the station's annual mean temperature from 2021 ran 0.4 C (0.8 F) lower than in the years before (possible change).
| Year | Shift (C) | Shift (F) | Strength | Neighbours |
|---|---|---|---|---|
| 2021 | -0.4 | -0.8 | possible | 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
2005 to 2025 against 1961 to 1990Over 2005 to 2025, Mtn Dell Dam had a mean temperature of 9.3 C (48.7 F) and 632.4 mm (24.9 in) of rain a year. The 3 stations whose 1961 to 1990 climate was closest to that are Arrowrock Dam (United States, 469 km away), Anderson Dam (United States, 423 km away) and Boise 7 N (United States, 496 km away).
| Twin station | Country | Distance away | Mean temperature, 1961-1990 | Rain a year, 1961-1990 | Climate difference |
|---|---|---|---|---|---|
| Arrowrock Dam | United States | 469 km (291 mi) | 9.3 C (48.8 F) | 490.9 mm (19.3 in) | 0.72 |
| Anderson Dam | United States | 423 km (263 mi) | 9.6 C (49.3 F) | 541.1 mm (21.3 in) | 0.87 |
| Boise 7 N | United States | 496 km (308 mi) | 9.6 C (49.3 F) | 493.0 mm (19.4 in) | 0.88 |
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 2026-10-13 (13 October 2026). Records are computed by this site and are not official.
Data as of . Last revised (2026-10-13).