Nagai climate — normals and trends
Nagai (Japan) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 9.1 °C and it receives 1,879 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 (22.2 °C on average) and the coldest is January (-2.8 °C). Rainfall peaks in July.
Nagai averages 129 frost days, 5 hot days (≥ 30 °C) and 223 rainy days per year.
Nagai has warmed by +2.6 °C between 1940 and 2025, or +0.30 °C per decade. This trend is statistically significant.
The number of frost days there went from about 146 to 112 per year over the period.
The hottest day of the period reached 33.7 °C (on 29 July 2025) and the coldest -16.3 °C (on 7 February 2020).
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
NagaiYamagata
- coords
- 38.10°, 140.03°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.1°C
Average daily high
12.8°C
Average daily low
5.7°C
Annual rainfall
1,879mm
Sunshine / day
7.5h
Mean relative humidity
82%
Average peak wind
13.2km/h
Seasonal range
25.0°C
Frost days (< 0 °C)
129 d/yr
Hot days (≥ 30 °C)
5 d/yr
Rainy days (≥ 1 mm)
223 d/yr
Annual snowfall
407.9 cm
Average feels-like high
11.6 °C
Average feels-like low
3.8 °C
Average peak gust
42.5 km/h
Tropical nights (≥ 20 °C)
23 d/yr
Solar radiation
13.2 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.6 °C
since 1940
+0.3 °C per decade · r² = 0.65 · 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
33.7 °C
29 July 2025
Coldest day
-16.3 °C
7 February 2020
Wettest day
130 mm
28 June 1966
Windiest day
51.6 km/h
14 December 2025
Strongest gust
149.4 km/h
4 April 2012
Hottest feels-like
39.4 °C
19 August 2023
Coldest feels-like
-21.0 °C
7 February 2020
Snowiest day
50.6 cm
24 December 1980
Sunniest day
14.3 h
8 June 1946
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 | 1.0 °C | +1.2 °C | 220 mm | +43 mm |
| Feb | 0.4 °C | -0.2 °C | 213 mm | +69 mm |
| Mar | 5.7 °C | +1.6 °C | 109 mm | -36 mm |
| Apr | 12.7 °C | +2.2 °C | 146 mm | +33 mm |
| May | 18.2 °C | +0.7 °C | 166 mm | +50 mm |
| Jun | 24.7 °C | +3.6 °C | 110 mm | -48 mm |
| Jul | 29.5 °C | +4.9 °C | 63 mm | -170 mm |
| Aug | 28.4 °C | +2.3 °C | 216 mm | +38 mm |
| Sep | 24.5 °C | +2.9 °C | 217 mm | +47 mm |
| Oct | 16.5 °C | +0.9 °C | 185 mm | +52 mm |
| Nov | 10.4 °C | +1.2 °C | 140 mm | +6 mm |
| Dec | 4.6 °C | +1.9 °C | 202 mm | +21 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 Nagai?
Nagai has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 9.1 °C and it receives 1,879 mm of precipitation per year.
What is the hottest day ever recorded in Nagai?
The hottest day measured in Nagai between 1940 and 2025 was 29 July 2025, reaching 33.7 °C.
What is the coldest day in Nagai?
The coldest day measured in Nagai between 1940 and 2025 was 7 February 2020, at -16.3 °C.
Does it snow in Nagai?
Yes. Nagai gets on average 407.9 cm of snow per year and has around 129 frost days.
Has the climate of Nagai warmed?
Yes: Nagai warmed by +2.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Nagai?
The wettest day measured in Nagai between 1940 and 2025 was 28 June 1966, with 130 mm of rain in 24 hours.
What was the windiest day in Nagai?
The windiest day measured in Nagai between 1940 and 2025 was 14 December 2025, with winds reaching 51.6 km/h.
What is the warmest month in Nagai?
The warmest month in Nagai is August (22.2 °C on average); the coldest is January (-2.8 °C).
How much does it rain in Nagai?
Nagai receives on average 1,879 mm of precipitation per year, spread over about 223 rainy days.
Is it sunny in Nagai?
Nagai gets on average 7.5 hours of sunshine per day, roughly 2,738 hours per year over 1940-2025.
What is the biggest single-day snowfall in Nagai?
The heaviest 24-hour snowfall measured in Nagai between 1940 and 2025 was 24 December 1980, with 50.6 cm.
Are there tropical nights in Nagai?
Yes: Nagai has on average 23 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Nagai?
In Nagai, between 1940 and 2025, the highest apparent temperature reached 39.4 °C on 19 August 2023, and the lowest was -21.0 °C on 7 February 2020.
Compare Nagai with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Nagai