Jōetsu climate — normals and trends
Jōetsu (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 13.7 °C and it receives 1,993 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 (26.3 °C on average) and the coldest is January (2.6 °C). Rainfall peaks in December.
Jōetsu averages 34 frost days, 24 hot days (≥ 30 °C) and 208 rainy days per year.
Jōetsu has warmed by +2.3 °C between 1940 and 2025, or +0.27 °C per decade. This trend is statistically significant.
The number of frost days there went from about 56 to 12 per year over the period.
The hottest day of the period reached 38.8 °C (on 10 August 2023) and the coldest -7.2 °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
JōetsuNiigata
- coords
- 37.15°, 138.24°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
13.7°C
Average daily high
16.7°C
Average daily low
10.8°C
Annual rainfall
1,993mm
Sunshine / day
8.7h
Mean relative humidity
77%
Average peak wind
18.4km/h
Seasonal range
23.7°C
Frost days (< 0 °C)
34 d/yr
Hot days (≥ 30 °C)
24 d/yr
Rainy days (≥ 1 mm)
208 d/yr
Annual snowfall
245.1 cm
Average feels-like high
16.2 °C
Average feels-like low
9.2 °C
Average peak gust
36.9 km/h
Tropical nights (≥ 20 °C)
73 d/yr
Solar radiation
14.5 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.3 °C
since 1940
+0.3 °C per decade · r² = 0.64 · p = < 0.001
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
38.8 °C
10 August 2023
Coldest day
-7.2 °C
12 February 1942
Wettest day
210 mm
8 July 1964
Windiest day
80.1 km/h
16 September 1961
Strongest gust
140.0 km/h
22 September 1998
Hottest feels-like
43.2 °C
17 August 2006
Coldest feels-like
-13.2 °C
7 March 1971
Snowiest day
36.5 cm
15 February 2014
Sunniest day
14.0 h
12 June 1986
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?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 5.9 °C | +1.0 °C | 244 mm | -1 mm |
| Feb | 4.5 °C | -0.5 °C | 300 mm | +114 mm |
| Mar | 9.7 °C | +1.1 °C | 130 mm | -13 mm |
| Apr | 15.1 °C | +0.2 °C | 84 mm | -15 mm |
| May | 20.0 °C | +0.1 °C | 92 mm | -6 mm |
| Jun | 25.4 °C | +1.8 °C | 166 mm | +38 mm |
| Jul | 31.6 °C | +4.1 °C | 22 mm | -174 mm |
| Aug | 31.1 °C | +1.6 °C | 236 mm | +93 mm |
| Sep | 27.9 °C | +2.7 °C | 214 mm | +42 mm |
| Oct | 20.3 °C | +0.9 °C | 248 mm | +90 mm |
| Nov | 14.3 °C | +0.5 °C | 196 mm | +18 mm |
| Dec | 9.9 °C | +1.7 °C | 279 mm | +31 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Jōetsu?
Jōetsu has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 13.7 °C and it receives 1,993 mm of precipitation per year.
What is the hottest day ever recorded in Jōetsu?
The hottest day measured in Jōetsu between 1940 and 2025 was 10 August 2023, reaching 38.8 °C.
What is the coldest day in Jōetsu?
The coldest day measured in Jōetsu between 1940 and 2025 was 12 February 1942, at -7.2 °C.
Does it snow in Jōetsu?
Yes. Jōetsu gets on average 245.1 cm of snow per year and has around 34 frost days.
Has the climate of Jōetsu warmed?
Yes: Jōetsu warmed by +2.3 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Jōetsu?
The wettest day measured in Jōetsu between 1940 and 2025 was 8 July 1964, with 210 mm of rain in 24 hours.
What was the windiest day in Jōetsu?
The windiest day measured in Jōetsu between 1940 and 2025 was 16 September 1961, with winds reaching 80.1 km/h.
What is the warmest month in Jōetsu?
The warmest month in Jōetsu is August (26.3 °C on average); the coldest is January (2.6 °C).
How much does it rain in Jōetsu?
Jōetsu receives on average 1,993 mm of precipitation per year, spread over about 208 rainy days.
Is it sunny in Jōetsu?
Jōetsu gets on average 8.7 hours of sunshine per day, roughly 3,175 hours per year over 1940-2025.
What is the biggest single-day snowfall in Jōetsu?
The heaviest 24-hour snowfall measured in Jōetsu between 1940 and 2025 was 15 February 2014, with 36.5 cm.
Are there tropical nights in Jōetsu?
Yes: Jōetsu has on average 73 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Jōetsu?
In Jōetsu, between 1940 and 2025, the highest apparent temperature reached 43.2 °C on 17 August 2006, and the lowest was -13.2 °C on 7 March 1971.
Compare Jōetsu with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Jōetsu