Itoigawa climate — normals and trends

Q: What is the climate of Itoigawa?

Itoigawa has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 11.7 °C and it receives 2,578 mm of precipitation per year.

Q: What is the hottest day ever recorded in Itoigawa?

The hottest day measured in Itoigawa between 1940 and 2025 was 29 July 2018, reaching 34.4 °C.

Q: What is the coldest day in Itoigawa?

The coldest day measured in Itoigawa between 1940 and 2025 was 12 February 1942, at -7.8 °C.

Q: Does it snow in Itoigawa?

Yes. Itoigawa gets on average 418.2 cm of snow per year and has around 65 frost days.

Q: Has the climate of Itoigawa warmed?

Yes: Itoigawa warmed by +2.5 °C between 1940 and 2025, a statistically significant trend.

Q: What is the wettest day in Itoigawa?

The wettest day measured in Itoigawa between 1940 and 2025 was 8 July 1964, with 198 mm of rain in 24 hours.

Q: What was the windiest day in Itoigawa?

The windiest day measured in Itoigawa between 1940 and 2025 was 16 September 1961, with winds reaching 57.7 km/h.

Q: What is the warmest month in Itoigawa?

The warmest month in Itoigawa is August (24.5 °C on average); the coldest is January (0.7 °C).

Q: How much does it rain in Itoigawa?

Itoigawa receives on average 2,578 mm of precipitation per year, spread over about 233 rainy days.

Q: Is it sunny in Itoigawa?

Itoigawa gets on average 8.8 hours of sunshine per day, roughly 3,212 hours per year over 1940-2025.

Itoigawa (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 11.7 °C and it receives 2,578 mm of precipitation per year.

These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.

The warmest month is August (24.5 °C on average) and the coldest is January (0.7 °C). Rainfall peaks in January.

Itoigawa averages 65 frost days, 1 hot days (≥ 30 °C) and 233 rainy days per year.

Itoigawa has warmed by +2.5 °C between 1940 and 2025, or +0.29 °C per decade. This trend is statistically significant.

The number of frost days there went from about 87 to 43 per year over the period.

The hottest day of the period reached 34.4 °C (on 29 July 2018) and the coldest -7.8 °C (on 12 February 1942).

Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.

Climate normals · ERA5

ItoigawaNiigata

coords: 37.03°, 137.85°
period: 1940–2025 · 86 yrs

CfaHumid subtropicalWarmest monthAugustColdest monthJanuaryWettest monthJanuaryDriest monthApril

Mean daily temperature

11.7°C

Average daily high

13.9°C

Average daily low

9.6°C

Annual rainfall

2,578mm

Sunshine / day

8.8h

Mean relative humidity

80%

Average peak wind

13.7km/h

Seasonal range

23.8°C

Frost days (< 0 °C)

65 d/yr

Hot days (≥ 30 °C)

1 d/yr

Rainy days (≥ 1 mm)

233 d/yr

Annual snowfall

418.2 cm

Average feels-like high

13.4 °C

Average feels-like low

8.1 °C

Average peak gust

38.4 km/h

Tropical nights (≥ 20 °C)

61 d/yr

Solar radiation

14.1 MJ/m²

Has the climate changed?

One stripe per year, 1940 to 2025

+2.5 °C

since 1940

+0.3 °C per decade · r² = 0.64 · p = < 0.001

19402025

Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).

A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.

Records for the period

Hottest day

34.4 °C

29 July 2018

Coldest day

-7.8 °C

12 February 1942

Wettest day

198 mm

8 July 1964

Windiest day

57.7 km/h

16 September 1961

Strongest gust

176.8 km/h

16 September 1961

Hottest feels-like

40.1 °C

3 September 2020

Coldest feels-like

-14.3 °C

26 February 1981

Snowiest day

38.9 cm

15 February 2014

Sunniest day

14.0 h

8 June 1940

Year	Hottest day	Coldest day	Annual mean	Rainfall	Hot days	Frost days
2025	30.3 °C1 September 2025	-3.8 °C5 February 2025	13.0 °C	2,687 mm	3	50
2024	32.0 °C23 August 2024	-3.6 °C11 March 2024	13.7 °C	2,745 mm	9	46
2023	33.5 °C10 August 2023	-6.6 °C25 January 2023	13.8 °C	2,759 mm	18	34
2022	32.2 °C6 September 2022	-3.1 °C17 February 2022	13.0 °C	2,597 mm	5	51
2021	31.6 °C9 August 2021	-4.7 °C8 January 2021	13.2 °C	2,755 mm	5	45
2020	32.0 °C3 September 2020	-5.7 °C7 February 2020	13.3 °C	3,013 mm	7	27
2019	32.8 °C15 August 2019	-3.2 °C9 February 2019	13.1 °C	2,710 mm	7	35
2018	34.4 °C29 July 2018	-5.1 °C24 January 2018	13.0 °C	2,437 mm	10	57
2017	31.6 °C7 August 2017	-4.3 °C14 January 2017	12.2 °C	2,790 mm	1	52
2016	30.4 °C29 August 2016	-4.2 °C8 February 2016	13.1 °C	2,525 mm	1	45
2015	30.1 °C13 July 2015	-4.5 °C9 February 2015	12.8 °C	2,271 mm	2	44
2014	30.0 °C5 August 2014	-4.8 °C5 February 2014	12.1 °C	2,647 mm	1	71
2013	29.8 °C31 August 2013	-4.8 °C25 February 2013	12.1 °C	2,759 mm	0	64
2012	29.8 °C17 September 2012	-5.0 °C27 December 2012	11.9 °C	2,619 mm	0	70
2011	29.4 °C10 August 2011	-4.5 °C30 January 2011	12.1 °C	2,492 mm	0	71
2010	30.2 °C6 August 2010	-4.9 °C4 February 2010	12.6 °C	2,658 mm	4	53
2009	29.2 °C15 July 2009	-5.5 °C22 February 2009	12.5 °C	2,422 mm	0	50
2008	29.5 °C3 August 2008	-4.1 °C14 January 2008	12.6 °C	2,080 mm	0	52
2007	30.4 °C3 August 2007	-4.3 °C16 March 2007	12.9 °C	2,099 mm	3	28
2006	31.1 °C17 August 2006	-5.2 °C4 February 2006	12.2 °C	2,607 mm	2	54
2005	30.5 °C7 September 2005	-4.6 °C2 March 2005	12.2 °C	2,415 mm	1	73
2004	31.6 °C1 August 2004	-4.8 °C22 January 2004	13.1 °C	2,672 mm	7	53
2003	30.5 °C13 September 2003	-5.3 °C29 January 2003	12.0 °C	2,404 mm	1	57
2002	30.3 °C1 September 2002	-3.9 °C2 January 2002	12.2 °C	2,512 mm	2	41
2001	29.2 °C1 August 2001	-5.2 °C14 January 2001	12.1 °C	2,577 mm	0	62
2000	31.2 °C30 July 2000	-4.5 °C26 January 2000	12.1 °C	2,650 mm	3	60
1999	30.7 °C6 August 1999	-5.7 °C3 February 1999	12.4 °C	2,760 mm	3	47
1998	28.7 °C25 July 1998	-3.7 °C24 January 1998	12.9 °C	2,851 mm	0	41
1997	29.5 °C9 August 1997	-6.8 °C22 January 1997	12.0 °C	2,586 mm	0	55
1996	30.4 °C14 August 1996	-6.7 °C2 February 1996	11.2 °C	2,559 mm	1	75
1995	29.9 °C24 August 1995	-4.5 °C26 December 1995	11.5 °C	2,534 mm	0	66
1994	31.1 °C14 August 1994	-3.4 °C17 December 1994	12.6 °C	1,909 mm	7	59
1993	28.1 °C25 August 1993	-2.9 °C16 December 1993	11.6 °C	2,777 mm	0	50
1992	28.7 °C16 August 1992	-2.7 °C16 December 1992	12.0 °C	2,239 mm	0	45
1991	29.5 °C26 July 1991	-5.0 °C24 February 1991	12.2 °C	2,875 mm	0	52
1990	32.0 °C22 August 1990	-4.7 °C25 January 1990	13.0 °C	2,281 mm	2	38
1989	30.9 °C27 July 1989	-3.7 °C28 January 1989	12.2 °C	2,480 mm	2	32
1988	28.5 °C22 August 1988	-5.8 °C3 February 1988	11.2 °C	2,788 mm	0	64
1987	29.9 °C31 August 1987	-3.9 °C25 January 1987	12.2 °C	2,157 mm	0	69
1986	30.7 °C29 August 1986	-5.0 °C16 February 1986	11.1 °C	2,369 mm	1	72
1985	29.5 °C1 September 1985	-5.6 °C27 January 1985	11.6 °C	2,945 mm	0	71
1984	29.5 °C16 August 1984	-6.3 °C7 February 1984	10.9 °C	2,456 mm	0	89
1983	30.1 °C14 August 1983	-4.4 °C13 February 1983	11.6 °C	2,881 mm	2	67
1982	29.1 °C28 August 1982	-4.9 °C31 January 1982	11.7 °C	2,603 mm	0	62
1981	29.4 °C30 July 1981	-6.9 °C26 February 1981	11.0 °C	2,923 mm	0	72
1980	28.3 °C11 September 1980	-3.6 °C6 February 1980	11.0 °C	2,941 mm	0	71
1979	29.8 °C18 August 1979	-4.6 °C26 December 1979	12.2 °C	2,736 mm	0	55
1978	30.5 °C20 August 1978	-5.8 °C16 February 1978	11.7 °C	2,546 mm	3	62
1977	29.8 °C4 August 1977	-6.9 °C16 February 1977	11.7 °C	2,641 mm	0	63
1976	28.2 °C26 July 1976	-5.1 °C23 January 1976	10.9 °C	3,292 mm	0	65
1975	30.0 °C18 August 1975	-5.1 °C18 February 1975	11.6 °C	2,742 mm	1	69
1974	28.9 °C11 August 1974	-5.5 °C11 February 1974	10.9 °C	2,690 mm	0	67
1973	29.8 °C18 August 1973	-4.7 °C24 February 1973	11.7 °C	2,300 mm	0	69
1972	29.7 °C9 August 1972	-3.6 °C25 February 1972	12.0 °C	3,316 mm	0	47
1971	31.1 °C5 August 1971	-5.9 °C7 March 1971	11.0 °C	2,860 mm	2	77
1970	29.0 °C24 July 1970	-5.8 °C16 January 1970	10.9 °C	2,570 mm	0	90
1969	28.6 °C22 August 1969	-5.6 °C6 February 1969	11.2 °C	2,751 mm	0	71
1968	28.7 °C27 July 1968	-5.2 °C21 February 1968	11.4 °C	2,367 mm	0	70
1967	28.6 °C28 July 1967	-7.4 °C16 January 1967	11.4 °C	2,506 mm	0	77
1966	28.3 °C21 August 1966	-6.4 °C20 January 1966	10.7 °C	2,806 mm	0	83
1965	29.2 °C6 August 1965	-7.0 °C6 January 1965	10.1 °C	2,952 mm	0	99
1964	31.1 °C24 August 1964	-3.5 °C20 January 1964	11.8 °C	3,214 mm	3	61
1963	29.9 °C10 August 1963	-5.5 °C24 January 1963	11.5 °C	2,454 mm	0	79
1962	30.5 °C3 August 1962	-5.4 °C14 February 1962	11.8 °C	2,193 mm	1	56
1961	30.3 °C4 September 1961	-5.1 °C15 February 1961	12.3 °C	2,750 mm	1	67
1960	29.6 °C5 August 1960	-4.8 °C24 January 1960	11.9 °C	2,550 mm	0	61
1959	29.6 °C1 September 1959	-4.5 °C18 January 1959	12.5 °C	2,622 mm	0	45
1958	29.3 °C18 August 1958	-4.9 °C4 January 1958	11.9 °C	2,429 mm	0	52
1957	30.8 °C21 August 1957	-4.9 °C20 February 1957	11.2 °C	2,544 mm	2	67
1956	29.4 °C9 September 1956	-5.1 °C19 February 1956	11.0 °C	2,700 mm	0	81
1955	29.5 °C30 August 1955	-5.1 °C12 February 1955	11.9 °C	2,743 mm	0	56
1954	30.5 °C14 September 1954	-4.9 °C22 February 1954	11.7 °C	2,326 mm	1	58
1953	29.0 °C30 July 1953	-4.4 °C9 February 1953	11.1 °C	3,162 mm	0	59
1952	27.4 °C19 August 1952	-6.7 °C5 February 1952	10.0 °C	2,884 mm	0	100
1951	29.4 °C19 August 1951	-6.3 °C22 January 1951	10.5 °C	2,258 mm	0	82
1950	29.3 °C28 July 1950	-6.0 °C6 January 1950	11.0 °C	2,387 mm	0	90
1949	28.1 °C16 August 1949	-4.4 °C4 March 1949	10.7 °C	2,263 mm	0	80
1948	28.5 °C9 September 1948	-5.7 °C24 February 1948	11.1 °C	2,198 mm	0	79
1947	28.0 °C14 August 1947	-7.3 °C3 February 1947	9.5 °C	2,500 mm	0	112
1946	28.8 °C29 July 1946	-5.2 °C9 February 1946	10.9 °C	2,326 mm	0	94
1945	27.7 °C26 August 1945	-7.3 °C20 February 1945	10.1 °C	3,066 mm	0	98
1944	27.3 °C22 August 1944	-6.0 °C2 February 1944	10.6 °C	2,013 mm	0	106
1943	26.5 °C12 August 1943	-6.6 °C14 February 1943	10.4 °C	2,096 mm	0	105
1942	28.2 °C3 August 1942	-7.8 °C12 February 1942	10.7 °C	1,674 mm	0	90
1941	28.7 °C23 August 1941	-7.3 °C9 February 1941	10.4 °C	2,190 mm	0	95
1940	27.2 °C14 July 1940	-7.1 °C9 January 1940	10.0 °C	2,238 mm	0	102

Normals computed over complete calendar years 1940–2025.

A specific year

Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?

Year

Across the whole year

Average daily high

15.2 °C

+1.3 °C

Hot days (≥ 30 °C)

3 d/yr

Frost days (< 0 °C)

50 d/yr

-15

Annual rainfall

2687 mm

+109 mm

Month by month

	High	vs. normal	Precipitation	vs. normal
Jan	2.9 °C	+0.4 °C	229 mm	-43 mm
Feb	2.1 °C	-0.5 °C	258 mm	+38 mm
Mar	6.6 °C	+1.1 °C	197 mm	+3 mm
Apr	12.1 °C	+1.3 °C	108 mm	-31 mm
May	16.7 °C	+0.3 °C	140 mm	-4 mm
Jun	22.3 °C	+2.0 °C	215 mm	+20 mm
Jul	27.1 °C	+2.5 °C	106 mm	-161 mm
Aug	28.0 °C	+1.6 °C	363 mm	+144 mm
Sep	25.4 °C	+2.6 °C	275 mm	+30 mm
Oct	18.4 °C	+1.2 °C	281 mm	+75 mm
Nov	12.0 °C	+0.3 °C	195 mm	-14 mm
Dec	7.6 °C	+1.9 °C	320 mm	+53 mm

The year's extremes

Hottest day

30.3 °C

1 Sep 2025

Coldest day

-3.8 °C

5 Feb 2025

Wettest day

91.7 mm

12 Aug 2025

Windiest day

34.8 km/h

16 Apr 2025

Strongest gust

99.4 km/h

16 Apr 2025

Hottest feels-like

36.9 °C

23 Aug 2025

Coldest feels-like

-10.2 °C

5 Feb 2025

Snowiest day

23.0 cm

26 Dec 2025

Sunniest day

14.0 h

5 Jun 2025

What was the weather like that day?

Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.

Date

Frequently asked questions

What is the climate of Itoigawa?

Itoigawa has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 11.7 °C and it receives 2,578 mm of precipitation per year.

What is the hottest day ever recorded in Itoigawa?

The hottest day measured in Itoigawa between 1940 and 2025 was 29 July 2018, reaching 34.4 °C.

What is the coldest day in Itoigawa?

The coldest day measured in Itoigawa between 1940 and 2025 was 12 February 1942, at -7.8 °C.

Does it snow in Itoigawa?

Yes. Itoigawa gets on average 418.2 cm of snow per year and has around 65 frost days.

Has the climate of Itoigawa warmed?

Yes: Itoigawa warmed by +2.5 °C between 1940 and 2025, a statistically significant trend.

What is the wettest day in Itoigawa?

The wettest day measured in Itoigawa between 1940 and 2025 was 8 July 1964, with 198 mm of rain in 24 hours.

What was the windiest day in Itoigawa?

The windiest day measured in Itoigawa between 1940 and 2025 was 16 September 1961, with winds reaching 57.7 km/h.

What is the warmest month in Itoigawa?

The warmest month in Itoigawa is August (24.5 °C on average); the coldest is January (0.7 °C).

How much does it rain in Itoigawa?

Itoigawa receives on average 2,578 mm of precipitation per year, spread over about 233 rainy days.

Is it sunny in Itoigawa?

Itoigawa gets on average 8.8 hours of sunshine per day, roughly 3,212 hours per year over 1940-2025.

What is the biggest single-day snowfall in Itoigawa?

The heaviest 24-hour snowfall measured in Itoigawa between 1940 and 2025 was 15 February 2014, with 38.9 cm.

Are there tropical nights in Itoigawa?

Yes: Itoigawa has on average 61 tropical nights per year (temperature staying above 20 °C), over 1940-2025.

What was the most extreme apparent temperature in Itoigawa?

In Itoigawa, between 1940 and 2025, the highest apparent temperature reached 40.1 °C on 3 September 2020, and the lowest was -14.3 °C on 26 February 1981.

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