Iwamizawa Weather Records (JA000047413)
Record envelope, standing records and threshold days for Iwamizawa (JA000047413), Japan, with 76 years of record.
Key Facts for Iwamizawa
- Iwamizawa (JA000047413) is a weather station in Japan at 43.22 latitude and 141.78 longitude, 51 m (167 ft) above sea level.
- The station reports from 1951 to 2026, 76 years of record.
- 1,464 records set at Iwamizawa still stand.
- Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
- Iwamizawa set a monthly record high minimum temperature of 18.1 C (64.6 F) on 5 October 2026 (provisional).
Provisional Records
Records set in the last 60 days are provisional until they clear the revision window.
About the Station
- Location: Japan, 43.22 latitude, 141.78 longitude.
- Elevation: 51 m (167 ft).
- Period of record: 1951 to 2026, 76 years.
- Eligible elements: tmax, tmin, prcp.
Daily Record Envelope and 2026
4 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 8.0 C (46.4 F) | -24.3 C (-11.7 F) | 5.2 C (41.4 F) | -15.9 C (3.4 F) |
| Feb | 12.7 C (54.9 F) | -23.0 C (-9.4 F) | 10.2 C (50.4 F) | -16.5 C (2.3 F) |
| Mar | 16.6 C (61.9 F) | -22.0 C (-7.6 F) | 12.4 C (54.3 F) | -6.0 C (21.2 F) |
| Apr | 26.8 C (80.2 F) | -10.9 C (12.4 F) | 19.6 C (67.3 F) | -1.2 C (29.8 F) |
| May | 33.1 C (91.6 F) | -3.6 C (25.5 F) | 25.1 C (77.2 F) | 1.1 C (34.0 F) |
| Jun | 33.6 C (92.5 F) | 2.5 C (36.5 F) | 28.8 C (83.8 F) | 9.3 C (48.7 F) |
| Jul | 35.5 C (95.9 F) | 5.2 C (41.4 F) | 30.9 C (87.6 F) | 12.6 C (54.7 F) |
| Aug | 35.1 C (95.2 F) | 6.9 C (44.4 F) | 31.4 C (88.5 F) | 13.7 C (56.7 F) |
| Sep | 32.7 C (90.9 F) | -1.0 C (30.2 F) | 26.6 C (79.9 F) | 9.4 C (48.9 F) |
| Oct | 26.0 C (78.8 F) | -3.3 C (26.1 F) | 18.6 C (65.5 F) | 7.7 C (45.9 F) |
| Nov | 20.5 C (68.9 F) | -14.6 C (5.7 F) | n/a | n/a |
| Dec | 14.1 C (57.4 F) | -22.6 C (-8.7 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1951 | 30 |
| 1952 | 29 |
| 1953 | 43 |
| 1954 | 33 |
| 1955 | 26 |
| 1956 | 15 |
| 1957 | 18 |
| 1958 | 9 |
| 1959 | 21 |
| 1960 | 25 |
| 1961 | 26 |
| 1962 | 15 |
| 1963 | 21 |
| 1964 | 30 |
| 1965 | 25 |
| 1966 | 42 |
| 1967 | 37 |
| 1968 | 20 |
| 1969 | 41 |
| 1970 | 27 |
| 1971 | 16 |
| 1972 | 14 |
| 1973 | 22 |
| 1974 | 13 |
| 1975 | 16 |
| 1976 | 22 |
| 1977 | 28 |
| 1978 | 33 |
| 1979 | 21 |
| 1980 | 39 |
| 1981 | 26 |
| 1982 | 22 |
| 1983 | 19 |
| 1984 | 16 |
| 1985 | 17 |
| 1986 | 14 |
| 1987 | 23 |
| 1988 | 20 |
| 1989 | 11 |
| 1991 | 9 |
| 1992 | 11 |
| 1993 | 15 |
| 1994 | 15 |
| 1995 | 6 |
| 1996 | 13 |
| 1997 | 11 |
| 1998 | 14 |
| 1999 | 17 |
| 2000 | 11 |
| 2001 | 18 |
| 2002 | 11 |
| 2003 | 2 |
| 2004 | 11 |
| 2006 | 8 |
| 2007 | 14 |
| 2008 | 15 |
| 2009 | 11 |
| 2010 | 17 |
| 2011 | 8 |
| 2012 | 21 |
| 2013 | 6 |
| 2014 | 13 |
| 2015 | 8 |
| 2016 | 15 |
| 2017 | 12 |
| 2018 | 10 |
| 2019 | 11 |
| 2020 | 26 |
| 2021 | 27 |
| 2022 | 15 |
| 2023 | 28 |
| 2024 | 13 |
| 2025 | 69 |
| 2026 | 28 |
All-Time Record Progression
7 new records| Date | Kind | Detail |
|---|---|---|
| 1981-08-01 | Record high maximum temperature | Record high maximum temperature 34.7 C (94.5 F) |
| 1981-08-04 | Record daily precipitation | Record daily precipitation 262.0 mm (10.3 in) |
| 2010-08-06 | Record high minimum temperature | Record high minimum temperature 24.6 C (76.3 F) |
| 2019-07-31 | Record high minimum temperature | Record high minimum temperature 24.9 C (76.8 F) |
| 2021-07-27 | Record high maximum temperature | Record high maximum temperature 35.0 C (95.0 F) |
| 2021-07-31 | Record high maximum temperature | Record high maximum temperature 35.5 C (95.9 F) |
| 2023-08-03 | Record high minimum temperature | Record high minimum temperature 25.2 C (77.4 F) |
Wettest Day of Each Month
Aug: 262.0 mm (10.3 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 62.0 mm (2.4 in) | 25 January 1996 |
| Feb | 53.5 mm (2.1 in) | 5 February 1969 |
| Mar | 56.9 mm (2.2 in) | 9 March 2018 |
| Apr | 73.2 mm (2.9 in) | 24 April 2011 |
| May | 71.1 mm (2.8 in) | 13 May 2000 |
| Jun | 88.9 mm (3.5 in) | 3 June 2015 |
| Jul | 212.5 mm (8.4 in) | 2 July 2026 |
| Aug | 262.0 mm (10.3 in) | 4 August 1981 |
| Sep | 99.1 mm (3.9 in) | 12 September 2012 |
| Oct | 85.5 mm (3.4 in) | 19 October 1979 |
| Nov | 73.2 mm (2.9 in) | 16 November 2011 |
| Dec | 53.1 mm (2.1 in) | 22 December 2023 |
Period of Record Coverage
1951 to 2026| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1951 | 364 | 100% | Yes |
| 1952 | 366 | 100% | Yes |
| 1953 | 359 | 98% | Yes |
| 1954 | 361 | 99% | Yes |
| 1955 | 358 | 98% | Yes |
| 1956 | 361 | 99% | Yes |
| 1957 | 359 | 98% | Yes |
| 1958 | 359 | 98% | Yes |
| 1959 | 362 | 99% | Yes |
| 1960 | 362 | 99% | Yes |
| 1961 | 358 | 98% | Yes |
| 1962 | 361 | 99% | Yes |
| 1963 | 359 | 98% | Yes |
| 1964 | 366 | 100% | Yes |
| 1965 | 365 | 100% | Yes |
| 1966 | 365 | 100% | Yes |
| 1967 | 365 | 100% | Yes |
| 1968 | 366 | 100% | Yes |
| 1969 | 365 | 100% | Yes |
| 1970 | 365 | 100% | Yes |
| 1971 | 365 | 100% | Yes |
| 1972 | 366 | 100% | Yes |
| 1973 | 365 | 100% | Yes |
| 1974 | 365 | 100% | Yes |
| 1975 | 365 | 100% | Yes |
| 1976 | 366 | 100% | Yes |
| 1977 | 365 | 100% | Yes |
| 1978 | 365 | 100% | Yes |
| 1979 | 365 | 100% | Yes |
| 1980 | 366 | 100% | Yes |
| 1981 | 365 | 100% | Yes |
| 1982 | 365 | 100% | Yes |
| 1983 | 365 | 100% | Yes |
| 1984 | 366 | 100% | Yes |
| 1985 | 365 | 100% | Yes |
| 1986 | 365 | 100% | Yes |
| 1987 | 365 | 100% | Yes |
| 1988 | 366 | 100% | Yes |
| 1989 | 365 | 100% | Yes |
| 1990 | 3 | 1% | No |
| 1991 | 274 | 75% | No |
| 1992 | 330 | 90% | Yes |
| 1993 | 344 | 94% | Yes |
| 1994 | 334 | 92% | Yes |
| 1995 | 331 | 91% | Yes |
| 1996 | 338 | 92% | Yes |
| 1997 | 320 | 88% | No |
| 1998 | 341 | 93% | Yes |
| 1999 | 318 | 87% | No |
| 2000 | 336 | 92% | Yes |
| 2001 | 290 | 79% | No |
| 2002 | 332 | 91% | Yes |
| 2003 | 334 | 92% | Yes |
| 2004 | 325 | 89% | No |
| 2006 | 342 | 94% | Yes |
| 2007 | 344 | 94% | Yes |
| 2008 | 336 | 92% | Yes |
| 2009 | 340 | 93% | Yes |
| 2010 | 330 | 90% | Yes |
| 2011 | 337 | 92% | Yes |
| 2012 | 342 | 93% | Yes |
| 2013 | 338 | 93% | Yes |
| 2014 | 339 | 93% | Yes |
| 2015 | 342 | 94% | Yes |
| 2016 | 339 | 93% | Yes |
| 2017 | 334 | 92% | Yes |
| 2018 | 331 | 91% | Yes |
| 2019 | 332 | 91% | Yes |
| 2020 | 317 | 87% | No |
| 2021 | 329 | 90% | Yes |
| 2022 | 336 | 92% | Yes |
| 2023 | 246 | 67% | No |
| 2024 | 283 | 77% | No |
| 2025 | 356 | 98% | Yes |
| 2026 | 271 | 74% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 5 October 2026 | Iwamizawa, JP | monthly high min (Provisional) | 18.1 C (64.6 F) | 1.6 C (2.9 F) | 71 years | 42 of 100 (Notable) |
| 30 September 2026 | Iwamizawa, JP | daily high min (Provisional) | 15.2 C (59.4 F) | 0.4 C (0.7 F) | 64 years | 27 of 100 (Routine) |
| 29 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 68.0 mm (2.7 in) | 24.1 mm (0.9 in) | 11 years | 27 of 100 (Routine) |
| 28 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 125.5 mm (4.9 in) | 93.0 mm (3.7 in) | 44 years | 60 of 100 (Major) |
| 28 September 2026 | Iwamizawa, JP | daily high min (Provisional) | 17.1 C (62.8 F) | 1.9 C (3.4 F) | 57 years | 29 of 100 (Routine) |
| 27 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 62.5 mm (2.5 in) | 24.4 mm (1.0 in) | 28 years | 32 of 100 (Routine) |
| 27 September 2026 | Iwamizawa, JP | daily high min (Provisional) | 15.7 C (60.3 F) | 2.7 C (4.9 F) | 52 years | 29 of 100 (Routine) |
| 26 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 33.5 mm (1.3 in) | 1.2 mm (0.05 in) | 67 years | 27 of 100 (Routine) |
| 16 September 2026 | Iwamizawa, JP | all-time rain (Provisional) | 271.5 mm (10.7 in) | 9.5 mm (0.37 in) | 45 years | 46 of 100 (Notable) |
| 15 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 53.0 mm (2.1 in) | 15.9 mm (0.6 in) | 1 year | 18 of 100 (Routine) |
| 14 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 60.5 mm (2.4 in) | 20.1 mm (0.8 in) | 21 years | 27 of 100 (Routine) |
| 13 September 2026 | Iwamizawa, JP | daily high min (Provisional) | 19.9 C (67.8 F) | 2.4 C (4.3 F) | 0 years | 13 of 100 (Routine) |
| 10 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 108.0 mm (4.3 in) | 35.9 mm (1.4 in) | 13 years | 36 of 100 (Notable) |
| 9 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 63.5 mm (2.5 in) | 22.6 mm (0.9 in) | 13 years | 27 of 100 (Routine) |
| 6 September 2026 | Iwamizawa, JP | daily rain (Provisional) | 91.0 mm (3.6 in) | 55.9 mm (2.2 in) | 9 years | 48 of 100 (Notable) |
| 3 September 2026 | Iwamizawa, JP | monthly rain (Provisional) | 119.5 mm (4.7 in) | 20.4 mm (0.8 in) | 13 years | 35 of 100 (Notable) |
| 28 August 2026 | Iwamizawa, JP | daily rain (Provisional) | 145.5 mm (5.7 in) | 66.5 mm (2.6 in) | 28 years | 46 of 100 (Notable) |
| 27 August 2026 | Iwamizawa, JP | daily rain (Provisional) | 144.0 mm (5.7 in) | 96.5 mm (3.8 in) | 47 years | 61 of 100 (Major) |
| 19 August 2026 | Iwamizawa, JP | daily high min (Provisional) | 23.8 C (74.8 F) | 2.0 C (3.6 F) | 51 years | 28 of 100 (Routine) |
| 18 August 2026 | Iwamizawa, JP | daily high min (Provisional) | 23.1 C (73.6 F) | 0.1 C (0.2 F) | 43 years | 19 of 100 (Routine) |
Climate Trend
40 complete years, 1951 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1951 | 7.1 C | -0.18 C |
| 1952 | 6.3 C | -1.00 C |
| 1953 | 6.3 C | -0.98 C |
| 1954 | 6.7 C | -0.58 C |
| 1955 | 7.6 C | +0.31 C |
| 1956 | 7.1 C | -0.26 C |
| 1957 | 7.3 C | +0.01 C |
| 1958 | 7.7 C | +0.43 C |
| 1959 | 7.9 C | +0.55 C |
| 1960 | 7.3 C | -0.03 C |
| 1961 | 8.1 C | +0.82 C |
| 1962 | 7.7 C | +0.40 C |
| 1963 | 8.1 C | +0.81 C |
| 1964 | 6.7 C | -0.59 C |
| 1965 | 6.8 C | -0.47 C |
| 1966 | 7.2 C | -0.09 C |
| 1967 | 7.3 C | +0.01 C |
| 1968 | 7.9 C | +0.63 C |
| 1969 | 6.5 C | -0.86 C |
| 1970 | 7.2 C | -0.12 C |
| 1971 | 7.0 C | -0.31 C |
| 1972 | 8.1 C | +0.79 C |
| 1973 | 7.9 C | +0.60 C |
| 1974 | 7.2 C | -0.09 C |
| 1975 | 7.4 C | +0.10 C |
| 1976 | 6.9 C | -0.42 C |
| 1977 | 6.8 C | -0.56 C |
| 1978 | 7.0 C | -0.31 C |
| 1979 | 7.4 C | +0.11 C |
| 1980 | 6.9 C | -0.46 C |
| 1981 | 6.7 C | -0.59 C |
| 1982 | 7.6 C | +0.26 C |
| 1983 | 6.9 C | -0.43 C |
| 1984 | 6.9 C | -0.42 C |
| 1985 | 7.2 C | -0.15 C |
| 1986 | 6.6 C | -0.69 C |
| 1987 | 7.2 C | -0.08 C |
| 1988 | 7.3 C | -0.06 C |
| 1989 | 8.4 C | +1.13 C |
| 2025 | 9.9 C | +2.61 C |
The annual mean temperature here has risen by 0.19 C (0.05 to 0.33) per decade over 1951 to 2025. In Fahrenheit: 0.3 F (0.1 to 0.6) per decade. The slope is a straight line fitted to 40 complete years; the brackets give its 95 percent interval.
| Measure | Per decade (C) | Per decade (F) | Period | Complete years | Reading |
|---|---|---|---|---|---|
| Annual mean temperature | 0.19 C (0.05 to 0.33) per decade | 0.3 F (0.1 to 0.6) per decade | 1951 to 2025 | 40 | Rise |
| Mean daily maximum | 0.1 C (-0.1 to 0.2) per decade | 0.1 F (-0.1 to 0.4) per decade | 1951 to 2025 | 40 | Not clearly different from zero |
| Mean daily minimum | 0.3 C (0.2 to 0.5) per decade | 0.6 F (0.3 to 0.8) per decade | 1951 to 2025 | 40 | 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
1951 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 35.5 C (95.9 F) | 2021 | 32.1 C (89.8 F) | 75 |
| Coldest night (TNn) | -24.3 C (-11.7 F) | 1957 | -19.1 C (-2.4 F) | 75 |
| Wettest day (Rx1day) | 271.5 mm (10.7 in) | 2026 | 58.9 mm (2.3 in) | 74 |
| Wettest five days (Rx5day) | 467.5 mm (18.4 in) | 2026 | 93.5 mm (3.7 in) | 74 |
| Longest dry spell (CDD) | 30 days | 2006 | 14 days | 72 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1951 | 34.0 C (93.2 F) |
| 1952 | 31.6 C (88.9 F) |
| 1953 | 31.4 C (88.5 F) |
| 1954 | 29.2 C (84.6 F) |
| 1955 | 33.4 C (92.1 F) |
| 1956 | 29.6 C (85.3 F) |
| 1957 | 29.6 C (85.3 F) |
| 1958 | 32.0 C (89.6 F) |
| 1959 | 32.0 C (89.6 F) |
| 1960 | 32.5 C (90.5 F) |
| 1961 | 30.9 C (87.6 F) |
| 1962 | 30.1 C (86.2 F) |
| 1963 | 31.6 C (88.9 F) |
| 1964 | 30.3 C (86.5 F) |
| 1965 | 32.1 C (89.8 F) |
| 1966 | 30.4 C (86.7 F) |
| 1967 | 32.2 C (90.0 F) |
| 1968 | 32.4 C (90.3 F) |
| 1969 | 31.4 C (88.5 F) |
| 1970 | 33.5 C (92.3 F) |
| 1971 | 32.6 C (90.7 F) |
| 1972 | 32.1 C (89.8 F) |
| 1973 | 33.1 C (91.6 F) |
| 1974 | 32.9 C (91.2 F) |
| 1975 | 31.0 C (87.8 F) |
| 1976 | 34.4 C (93.9 F) |
| 1977 | 32.1 C (89.8 F) |
| 1978 | 33.5 C (92.3 F) |
| 1979 | 30.7 C (87.3 F) |
| 1980 | 30.8 C (87.4 F) |
| 1981 | 34.7 C (94.5 F) |
| 1982 | 33.0 C (91.4 F) |
| 1983 | 32.7 C (90.9 F) |
| 1984 | 32.7 C (90.9 F) |
| 1985 | 33.8 C (92.8 F) |
| 1986 | 33.6 C (92.5 F) |
| 1987 | 30.8 C (87.4 F) |
| 1988 | 33.0 C (91.4 F) |
| 1989 | 33.3 C (91.9 F) |
| 1990 | 25.9 C (78.6 F) |
| 1991 | 30.6 C (87.1 F) |
| 1992 | 30.7 C (87.3 F) |
| 1993 | 29.9 C (85.8 F) |
| 1994 | 34.7 C (94.5 F) |
| 1995 | 31.6 C (88.9 F) |
| 1996 | 31.2 C (88.2 F) |
| 1997 | 31.8 C (89.2 F) |
| 1998 | 30.8 C (87.4 F) |
| 1999 | 34.6 C (94.3 F) |
| 2000 | 33.9 C (93.0 F) |
| 2001 | 30.3 C (86.5 F) |
| 2002 | 30.4 C (86.7 F) |
| 2003 | 29.7 C (85.5 F) |
| 2004 | 32.2 C (90.0 F) |
| 2006 | 33.8 C (92.8 F) |
| 2007 | 34.6 C (94.3 F) |
| 2008 | 31.2 C (88.2 F) |
| 2009 | 31.5 C (88.7 F) |
| 2010 | 32.8 C (91.0 F) |
| 2011 | 32.8 C (91.0 F) |
| 2012 | 32.0 C (89.6 F) |
| 2013 | 31.6 C (88.9 F) |
| 2014 | 33.6 C (92.5 F) |
| 2015 | 31.2 C (88.2 F) |
| 2016 | 32.4 C (90.3 F) |
| 2017 | 33.0 C (91.4 F) |
| 2018 | 32.1 C (89.8 F) |
| 2019 | 33.4 C (92.1 F) |
| 2020 | 32.7 C (90.9 F) |
| 2021 | 35.5 C (95.9 F) |
| 2022 | 32.3 C (90.1 F) |
| 2023 | 32.8 C (91.0 F) |
| 2024 | 33.7 C (92.7 F) |
| 2025 | 34.3 C (93.7 F) |
| 2026 | 31.4 C (88.5 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1951 | -22.6 C (-8.7 F) |
| 1952 | -22.6 C (-8.7 F) |
| 1953 | -22.5 C (-8.5 F) |
| 1954 | -23.0 C (-9.4 F) |
| 1955 | -20.7 C (-5.3 F) |
| 1956 | -21.6 C (-6.9 F) |
| 1957 | -24.3 C (-11.7 F) |
| 1958 | -17.9 C (-0.2 F) |
| 1959 | -20.7 C (-5.3 F) |
| 1960 | -23.5 C (-10.3 F) |
| 1961 | -20.6 C (-5.1 F) |
| 1962 | -21.2 C (-6.2 F) |
| 1963 | -18.8 C (-1.8 F) |
| 1964 | -21.8 C (-7.2 F) |
| 1965 | -22.0 C (-7.6 F) |
| 1966 | -21.3 C (-6.3 F) |
| 1967 | -23.4 C (-10.1 F) |
| 1968 | -22.7 C (-8.9 F) |
| 1969 | -19.0 C (-2.2 F) |
| 1970 | -22.3 C (-8.1 F) |
| 1971 | -19.2 C (-2.6 F) |
| 1972 | -17.4 C (0.7 F) |
| 1973 | -16.6 C (2.1 F) |
| 1974 | -18.1 C (-0.6 F) |
| 1975 | -20.3 C (-4.5 F) |
| 1976 | -18.9 C (-2.0 F) |
| 1977 | -22.0 C (-7.6 F) |
| 1978 | -21.9 C (-7.4 F) |
| 1979 | -18.9 C (-2.0 F) |
| 1980 | -19.6 C (-3.3 F) |
| 1981 | -19.8 C (-3.6 F) |
| 1982 | -21.9 C (-7.4 F) |
| 1983 | -18.4 C (-1.1 F) |
| 1984 | -20.8 C (-5.4 F) |
| 1985 | -21.1 C (-6.0 F) |
| 1986 | -22.9 C (-9.2 F) |
| 1987 | -18.2 C (-0.8 F) |
| 1988 | -17.8 C (0.0 F) |
| 1989 | -16.5 C (2.3 F) |
| 1990 | 17.5 C (63.5 F) |
| 1991 | -14.9 C (5.2 F) |
| 1992 | -16.0 C (3.2 F) |
| 1993 | -16.5 C (2.3 F) |
| 1994 | -21.3 C (-6.3 F) |
| 1995 | -19.1 C (-2.4 F) |
| 1996 | -16.4 C (2.5 F) |
| 1997 | -17.5 C (0.5 F) |
| 1998 | -23.0 C (-9.4 F) |
| 1999 | -16.4 C (2.5 F) |
| 2000 | -20.7 C (-5.3 F) |
| 2001 | -19.8 C (-3.6 F) |
| 2002 | -18.3 C (-0.9 F) |
| 2003 | -18.1 C (-0.6 F) |
| 2004 | -14.1 C (6.6 F) |
| 2006 | -16.8 C (1.8 F) |
| 2007 | -14.5 C (5.9 F) |
| 2008 | -20.6 C (-5.1 F) |
| 2009 | -14.2 C (6.4 F) |
| 2010 | -17.4 C (0.7 F) |
| 2011 | -15.4 C (4.3 F) |
| 2012 | -20.4 C (-4.7 F) |
| 2013 | -16.6 C (2.1 F) |
| 2014 | -20.7 C (-5.3 F) |
| 2015 | -17.2 C (1.0 F) |
| 2016 | -15.8 C (3.6 F) |
| 2017 | -19.5 C (-3.1 F) |
| 2018 | -16.6 C (2.1 F) |
| 2019 | -16.7 C (1.9 F) |
| 2020 | -19.3 C (-2.7 F) |
| 2021 | -16.8 C (1.8 F) |
| 2022 | -17.8 C (0.0 F) |
| 2023 | -19.7 C (-3.5 F) |
| 2024 | -14.5 C (5.9 F) |
| 2025 | -13.3 C (8.1 F) |
| 2026 | -16.5 C (2.3 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1951 | 40.4 mm (1.6 in) |
| 1952 | 37.7 mm (1.5 in) |
| 1953 | 45.1 mm (1.8 in) |
| 1954 | 54.5 mm (2.1 in) |
| 1955 | 57.6 mm (2.3 in) |
| 1956 | 73.5 mm (2.9 in) |
| 1957 | 59.8 mm (2.4 in) |
| 1958 | 99.2 mm (3.9 in) |
| 1959 | 32.3 mm (1.3 in) |
| 1960 | 41.2 mm (1.6 in) |
| 1961 | 146.7 mm (5.8 in) |
| 1962 | 134.4 mm (5.3 in) |
| 1963 | 36.8 mm (1.4 in) |
| 1964 | 65.6 mm (2.6 in) |
| 1965 | 58.3 mm (2.3 in) |
| 1966 | 119.6 mm (4.7 in) |
| 1967 | 61.1 mm (2.4 in) |
| 1968 | 40.5 mm (1.6 in) |
| 1969 | 53.5 mm (2.1 in) |
| 1970 | 55.0 mm (2.2 in) |
| 1971 | 55.5 mm (2.2 in) |
| 1972 | 34.0 mm (1.3 in) |
| 1973 | 62.5 mm (2.5 in) |
| 1974 | 49.5 mm (1.9 in) |
| 1975 | 179.5 mm (7.1 in) |
| 1976 | 39.5 mm (1.6 in) |
| 1977 | 61.5 mm (2.4 in) |
| 1978 | 29.5 mm (1.2 in) |
| 1979 | 85.5 mm (3.4 in) |
| 1980 | 44.5 mm (1.8 in) |
| 1981 | 262.0 mm (10.3 in) |
| 1982 | 72.0 mm (2.8 in) |
| 1983 | 35.0 mm (1.4 in) |
| 1984 | 24.0 mm (0.9 in) |
| 1985 | 91.0 mm (3.6 in) |
| 1986 | 77.0 mm (3.0 in) |
| 1987 | 56.0 mm (2.2 in) |
| 1988 | 113.5 mm (4.5 in) |
| 1989 | 60.0 mm (2.4 in) |
| 1990 | n/a |
| 1991 | 58.9 mm (2.3 in) |
| 1992 | 63.0 mm (2.5 in) |
| 1993 | 29.5 mm (1.2 in) |
| 1994 | 61.0 mm (2.4 in) |
| 1995 | 55.9 mm (2.2 in) |
| 1996 | 63.0 mm (2.5 in) |
| 1997 | 58.9 mm (2.3 in) |
| 1998 | 79.0 mm (3.1 in) |
| 1999 | 58.9 mm (2.3 in) |
| 2000 | 71.1 mm (2.8 in) |
| 2001 | 47.0 mm (1.9 in) |
| 2002 | 34.0 mm (1.3 in) |
| 2003 | 51.1 mm (2.0 in) |
| 2004 | 65.0 mm (2.6 in) |
| 2006 | 65.0 mm (2.6 in) |
| 2007 | 45.0 mm (1.8 in) |
| 2008 | 31.0 mm (1.2 in) |
| 2009 | 59.9 mm (2.4 in) |
| 2010 | 48.0 mm (1.9 in) |
| 2011 | 73.2 mm (2.9 in) |
| 2012 | 99.1 mm (3.9 in) |
| 2013 | 61.0 mm (2.4 in) |
| 2014 | 52.1 mm (2.1 in) |
| 2015 | 88.9 mm (3.5 in) |
| 2016 | 102.1 mm (4.0 in) |
| 2017 | 54.1 mm (2.1 in) |
| 2018 | 58.9 mm (2.3 in) |
| 2019 | 103.1 mm (4.1 in) |
| 2020 | 70.1 mm (2.8 in) |
| 2021 | 48.0 mm (1.9 in) |
| 2022 | 124.0 mm (4.9 in) |
| 2023 | 53.1 mm (2.1 in) |
| 2024 | 40.9 mm (1.6 in) |
| 2025 | 16.0 mm (0.6 in) |
| 2026 | 271.5 mm (10.7 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1951 | 59.3 mm (2.3 in) |
| 1952 | 70.2 mm (2.8 in) |
| 1953 | 87.6 mm (3.4 in) |
| 1954 | 81.1 mm (3.2 in) |
| 1955 | 87.1 mm (3.4 in) |
| 1956 | 103.6 mm (4.1 in) |
| 1957 | 96.0 mm (3.8 in) |
| 1958 | 139.9 mm (5.5 in) |
| 1959 | 59.9 mm (2.4 in) |
| 1960 | 91.6 mm (3.6 in) |
| 1961 | 237.3 mm (9.3 in) |
| 1962 | 261.7 mm (10.3 in) |
| 1963 | 80.9 mm (3.2 in) |
| 1964 | 93.4 mm (3.7 in) |
| 1965 | 169.1 mm (6.7 in) |
| 1966 | 223.8 mm (8.8 in) |
| 1967 | 95.9 mm (3.8 in) |
| 1968 | 95.0 mm (3.7 in) |
| 1969 | 124.5 mm (4.9 in) |
| 1970 | 87.0 mm (3.4 in) |
| 1971 | 103.5 mm (4.1 in) |
| 1972 | 89.0 mm (3.5 in) |
| 1973 | 101.0 mm (4.0 in) |
| 1974 | 98.0 mm (3.9 in) |
| 1975 | 236.0 mm (9.3 in) |
| 1976 | 71.5 mm (2.8 in) |
| 1977 | 101.0 mm (4.0 in) |
| 1978 | 59.5 mm (2.3 in) |
| 1979 | 140.0 mm (5.5 in) |
| 1980 | 77.0 mm (3.0 in) |
| 1981 | 410.0 mm (16.1 in) |
| 1982 | 83.0 mm (3.3 in) |
| 1983 | 60.0 mm (2.4 in) |
| 1984 | 65.0 mm (2.6 in) |
| 1985 | 93.5 mm (3.7 in) |
| 1986 | 126.5 mm (5.0 in) |
| 1987 | 58.5 mm (2.3 in) |
| 1988 | 195.0 mm (7.7 in) |
| 1989 | 95.0 mm (3.7 in) |
| 1990 | n/a |
| 1991 | 22.9 mm (0.9 in) |
| 1992 | 44.0 mm (1.7 in) |
| 1993 | 25.8 mm (1.0 in) |
| 1994 | 48.0 mm (1.9 in) |
| 1995 | 59.9 mm (2.4 in) |
| 1996 | 95.0 mm (3.7 in) |
| 1997 | 117.3 mm (4.6 in) |
| 1998 | 49.1 mm (1.9 in) |
| 1999 | 47.5 mm (1.9 in) |
| 2000 | 69.8 mm (2.7 in) |
| 2001 | 62.7 mm (2.5 in) |
| 2002 | 79.9 mm (3.1 in) |
| 2003 | 79.0 mm (3.1 in) |
| 2004 | 76.9 mm (3.0 in) |
| 2006 | 82.5 mm (3.2 in) |
| 2007 | 71.4 mm (2.8 in) |
| 2008 | 55.8 mm (2.2 in) |
| 2009 | 79.7 mm (3.1 in) |
| 2010 | 109.8 mm (4.3 in) |
| 2011 | 181.8 mm (7.2 in) |
| 2012 | 246.1 mm (9.7 in) |
| 2013 | 121.2 mm (4.8 in) |
| 2014 | 109.2 mm (4.3 in) |
| 2015 | 101.1 mm (4.0 in) |
| 2016 | 220.7 mm (8.7 in) |
| 2017 | 95.4 mm (3.8 in) |
| 2018 | 109.7 mm (4.3 in) |
| 2019 | 127.0 mm (5.0 in) |
| 2020 | 82.6 mm (3.3 in) |
| 2021 | 90.4 mm (3.6 in) |
| 2022 | 140.0 mm (5.5 in) |
| 2023 | 94.2 mm (3.7 in) |
| 2024 | 94.3 mm (3.7 in) |
| 2025 | 48.5 mm (1.9 in) |
| 2026 | 467.5 mm (18.4 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1951 | 9 days |
| 1952 | 13 days |
| 1953 | 16 days |
| 1954 | 21 days |
| 1955 | 17 days |
| 1956 | 13 days |
| 1957 | 13 days |
| 1958 | 16 days |
| 1959 | 12 days |
| 1960 | 10 days |
| 1961 | 11 days |
| 1962 | 14 days |
| 1963 | 18 days |
| 1964 | 11 days |
| 1965 | 8 days |
| 1966 | 14 days |
| 1967 | 12 days |
| 1968 | 17 days |
| 1969 | 9 days |
| 1970 | 12 days |
| 1971 | 15 days |
| 1972 | 19 days |
| 1973 | 17 days |
| 1974 | 19 days |
| 1975 | 11 days |
| 1976 | 11 days |
| 1977 | 19 days |
| 1978 | 14 days |
| 1979 | 24 days |
| 1980 | 18 days |
| 1981 | 16 days |
| 1982 | 18 days |
| 1983 | 11 days |
| 1984 | 28 days |
| 1985 | 20 days |
| 1986 | 12 days |
| 1987 | 11 days |
| 1988 | 24 days |
| 1989 | 20 days |
| 1990 | n/a |
| 1991 | 1 day |
| 1992 | 1 day |
| 1993 | 1 day |
| 1994 | 1 day |
| 1995 | 2 days |
| 1996 | 1 day |
| 1997 | 1 day |
| 1998 | 2 days |
| 1999 | 6 days |
| 2000 | n/a |
| 2001 | n/a |
| 2002 | 2 days |
| 2003 | 7 days |
| 2004 | 9 days |
| 2006 | 30 days |
| 2007 | 3 days |
| 2008 | 15 days |
| 2009 | 14 days |
| 2010 | 10 days |
| 2011 | 14 days |
| 2012 | 18 days |
| 2013 | 15 days |
| 2014 | 24 days |
| 2015 | 20 days |
| 2016 | 9 days |
| 2017 | 11 days |
| 2018 | 16 days |
| 2019 | 19 days |
| 2020 | 11 days |
| 2021 | 26 days |
| 2022 | 16 days |
| 2023 | 9 days |
| 2024 | 15 days |
| 2025 | 8 days |
| 2026 | 20 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
40 years with a frostAcross 40 years with a frost, the median last spring frost at Iwamizawa falls on 29 April and the median first autumn frost on 23 October, which leaves a median of 175 days between them.
Fitted over all years, the growing season changes by +3.2 days per decade at this station.
| Measure | Median, all years | Earliest period | Recent period (1961 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 29 April | n/a | 28 April | n/a | -1.4 days per decade |
| First autumn frost | 23 October | n/a | 23 October | n/a | +1.8 days per decade |
| Growing days | 175 days | n/a | 176 days | n/a | +3.2 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
53 years, 1951 to 2022A day with at least 59.6 mm (2.3 in) of rain is expected about once in 2 years. A day with at least 245.5 mm (9.7 in) of rain is expected about once in 100 years.
| Expected about once in | A day with at least | Note |
|---|---|---|
| 2 years | 59.6 mm (2.3 in) | |
| 5 years | 90.0 mm (3.5 in) | |
| 10 years | 116.2 mm (4.6 in) | |
| 25 years | 158.3 mm (6.2 in) | |
| 50 years | 197.8 mm (7.8 in) | |
| 100 years | 245.5 mm (9.7 in) | Longer than the 53 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, 53 years of values from 1951 to 2022.
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: 262.0 mm (10.3 in) in 1981; 179.5 mm (7.1 in) in 1975; 146.7 mm (5.8 in) in 1961.
Station Changes
2 suspected2 changes were suspected in the annual mean temperature of Iwamizawa, at 1960 and 1976. Each is measured against neighbouring stations.
- Relative to 5 neighbouring stations, the station's annual mean temperature from 1960 ran 0.2 C (0.4 F) higher than in the years before (likely change).
- Relative to 5 neighbouring stations, the station's annual mean temperature from 1976 ran 0.1 C (0.2 F) lower than in the years before (possible change).
| Year | Shift (C) | Shift (F) | Strength | Neighbours |
|---|---|---|---|---|
| 1960 | +0.2 | +0.4 | likely | 5 |
| 1976 | -0.1 | -0.2 | 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.
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).