Suwa climate — normals and trends
Suwa (Japan) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 8.9 °C and it receives 1,612 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 (21.8 °C on average) and the coldest is January (-4.8 °C). Rainfall peaks in July.
Suwa averages 135 frost days, 4 hot days (≥ 30 °C) and 161 rainy days per year.
Suwa has warmed by +3.4 °C between 1940 and 2025, or +0.39 °C per decade. This trend is statistically significant.
The number of frost days there went from about 153 to 118 per year over the period.
The hottest day of the period reached 33.5 °C (on 5 August 2018) and the coldest -24.6 °C (on 25 January 1940).
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
SuwaNagano
- coords
- 36.04°, 138.11°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
8.9°C
Average daily high
14.0°C
Average daily low
4.3°C
Annual rainfall
1,612mm
Sunshine / day
8.8h
Mean relative humidity
72%
Average peak wind
9.7km/h
Seasonal range
26.6°C
Frost days (< 0 °C)
135 d/yr
Hot days (≥ 30 °C)
4 d/yr
Rainy days (≥ 1 mm)
161 d/yr
Annual snowfall
160.8 cm
Average feels-like high
12.7 °C
Average feels-like low
2.4 °C
Average peak gust
35.2 km/h
Tropical nights (≥ 20 °C)
5 d/yr
Solar radiation
15.2 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+3.4 °C
since 1940
+0.4 °C per decade · r² = 0.70 · 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
33.5 °C
5 August 2018
Coldest day
-24.6 °C
25 January 1940
Wettest day
156 mm
5 October 1945
Windiest day
41.4 km/h
27 September 1959
Strongest gust
182.5 km/h
27 September 1959
Hottest feels-like
37.5 °C
15 July 2018
Coldest feels-like
-29.9 °C
25 January 1940
Snowiest day
38.4 cm
15 February 2014
Sunniest day
14.0 h
9 June 1940
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 | 3.0 °C | +2.2 °C | 53 mm | -22 mm |
| Feb | 2.5 °C | +0.5 °C | 61 mm | -24 mm |
| Mar | 9.3 °C | +3.0 °C | 146 mm | +20 mm |
| Apr | 15.3 °C | +2.0 °C | 104 mm | -26 mm |
| May | 19.9 °C | +1.4 °C | 142 mm | +1 mm |
| Jun | 24.6 °C | +3.0 °C | 178 mm | -25 mm |
| Jul | 29.1 °C | +3.9 °C | 122 mm | -89 mm |
| Aug | 29.5 °C | +3.1 °C | 92 mm | -50 mm |
| Sep | 25.6 °C | +3.2 °C | 163 mm | -14 mm |
| Oct | 17.6 °C | +1.2 °C | 169 mm | +18 mm |
| Nov | 10.9 °C | +0.3 °C | 56 mm | -38 mm |
| Dec | 5.6 °C | +1.6 °C | 87 mm | +11 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 Suwa?
Suwa has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 8.9 °C and it receives 1,612 mm of precipitation per year.
What is the hottest day ever recorded in Suwa?
The hottest day measured in Suwa between 1940 and 2025 was 5 August 2018, reaching 33.5 °C.
What is the coldest day in Suwa?
The coldest day measured in Suwa between 1940 and 2025 was 25 January 1940, at -24.6 °C.
Does it snow in Suwa?
Yes. Suwa gets on average 160.8 cm of snow per year and has around 135 frost days.
Has the climate of Suwa warmed?
Yes: Suwa warmed by +3.4 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Suwa?
The wettest day measured in Suwa between 1940 and 2025 was 5 October 1945, with 156 mm of rain in 24 hours.
What was the windiest day in Suwa?
The windiest day measured in Suwa between 1940 and 2025 was 27 September 1959, with winds reaching 41.4 km/h.
What is the warmest month in Suwa?
The warmest month in Suwa is August (21.8 °C on average); the coldest is January (-4.8 °C).
How much does it rain in Suwa?
Suwa receives on average 1,612 mm of precipitation per year, spread over about 161 rainy days.
Is it sunny in Suwa?
Suwa 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 Suwa?
The heaviest 24-hour snowfall measured in Suwa between 1940 and 2025 was 15 February 2014, with 38.4 cm.
Are there tropical nights in Suwa?
Yes: Suwa has on average 5 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Suwa?
In Suwa, between 1940 and 2025, the highest apparent temperature reached 37.5 °C on 15 July 2018, and the lowest was -29.9 °C on 25 January 1940.
Compare Suwa with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Suwa