Seto climate — normals and trends
Seto (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 15.1 °C and it receives 1,508 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 (27.1 °C on average) and the coldest is January (3.6 °C). Rainfall peaks in July.
Seto averages 62 frost days, 49 hot days (≥ 30 °C) and 127 rainy days per year.
Seto has warmed by +3.2 °C between 1940 and 2025, or +0.38 °C per decade. This trend is statistically significant.
The number of frost days there went from about 92 to 32 per year over the period.
The hottest day of the period reached 40.0 °C (on 1 July 2022) and the coldest -13.9 °C (on 18 February 1947).
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
SetoAichi
- coords
- 35.23°, 137.10°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
15.1°C
Average daily high
19.9°C
Average daily low
10.5°C
Annual rainfall
1,508mm
Sunshine / day
8.6h
Mean relative humidity
72%
Average peak wind
14.8km/h
Seasonal range
23.5°C
Frost days (< 0 °C)
62 d/yr
Hot days (≥ 30 °C)
49 d/yr
Rainy days (≥ 1 mm)
127 d/yr
Annual snowfall
4.6 cm
Average feels-like high
19.7 °C
Average feels-like low
9.8 °C
Average peak gust
31.6 km/h
Tropical nights (≥ 20 °C)
81 d/yr
Solar radiation
14.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+3.2 °C
since 1940
+0.4 °C per decade · r² = 0.72 · 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
40.0 °C
1 July 2022
Coldest day
-13.9 °C
18 February 1947
Wettest day
192 mm
16 September 1972
Windiest day
96.5 km/h
26 September 1959
Strongest gust
208.8 km/h
26 September 1959
Hottest feels-like
45.6 °C
29 July 2025
Coldest feels-like
-18.4 °C
18 February 1947
Snowiest day
20.0 cm
15 February 1968
Sunniest day
14.0 h
10 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 | 10.0 °C | +1.3 °C | 25 mm | -20 mm |
| Feb | 8.9 °C | -0.8 °C | 19 mm | -39 mm |
| Mar | 15.2 °C | +1.7 °C | 120 mm | +18 mm |
| Apr | 20.9 °C | +2.0 °C | 118 mm | -10 mm |
| May | 24.2 °C | +1.0 °C | 171 mm | +23 mm |
| Jun | 28.5 °C | +2.2 °C | 225 mm | +22 mm |
| Jul | 34.9 °C | +5.1 °C | 77 mm | -133 mm |
| Aug | 35.8 °C | +4.3 °C | 95 mm | -48 mm |
| Sep | 31.0 °C | +3.3 °C | 183 mm | -10 mm |
| Oct | 23.5 °C | +1.4 °C | 158 mm | +12 mm |
| Nov | 17.1 °C | +0.5 °C | 33 mm | -49 mm |
| Dec | 12.3 °C | +1.2 °C | 57 mm | +9 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 Seto?
Seto has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 15.1 °C and it receives 1,508 mm of precipitation per year.
What is the hottest day ever recorded in Seto?
The hottest day measured in Seto between 1940 and 2025 was 1 July 2022, reaching 40.0 °C.
What is the coldest day in Seto?
The coldest day measured in Seto between 1940 and 2025 was 18 February 1947, at -13.9 °C.
Does it snow in Seto?
Yes. Seto gets on average 4.6 cm of snow per year and has around 62 frost days.
Has the climate of Seto warmed?
Yes: Seto warmed by +3.2 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Seto?
The wettest day measured in Seto between 1940 and 2025 was 16 September 1972, with 192 mm of rain in 24 hours.
What was the windiest day in Seto?
The windiest day measured in Seto between 1940 and 2025 was 26 September 1959, with winds reaching 96.5 km/h.
What is the warmest month in Seto?
The warmest month in Seto is August (27.1 °C on average); the coldest is January (3.6 °C).
How much does it rain in Seto?
Seto receives on average 1,508 mm of precipitation per year, spread over about 127 rainy days.
Is it sunny in Seto?
Seto gets on average 8.6 hours of sunshine per day, roughly 3,139 hours per year over 1940-2025.
What is the biggest single-day snowfall in Seto?
The heaviest 24-hour snowfall measured in Seto between 1940 and 2025 was 15 February 1968, with 20.0 cm.
Are there tropical nights in Seto?
Yes: Seto has on average 81 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Seto?
In Seto, between 1940 and 2025, the highest apparent temperature reached 45.6 °C on 29 July 2025, and the lowest was -18.4 °C on 18 February 1947.
Compare Seto with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Seto