Oshima climate — normals and trends
Oshima (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 14.4 °C and it receives 2,049 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 February (4.2 °C). Rainfall peaks in December.
Oshima averages 9 frost days, 6 hot days (≥ 30 °C) and 197 rainy days per year.
Oshima has warmed by +1.6 °C between 1940 and 2025, or +0.18 °C per decade. This trend is statistically significant.
The number of frost days there went from about 17 to 1 per year over the period.
The hottest day of the period reached 35.1 °C (on 15 August 2019) and the coldest -4.9 °C (on 14 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
OshimaIshikawa
- coords
- 36.99°, 136.77°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
14.4°C
Average daily high
16.2°C
Average daily low
12.6°C
Annual rainfall
2,049mm
Sunshine / day
8.8h
Mean relative humidity
76%
Average peak wind
25.4km/h
Seasonal range
22.1°C
Frost days (< 0 °C)
9 d/yr
Hot days (≥ 30 °C)
6 d/yr
Rainy days (≥ 1 mm)
197 d/yr
Annual snowfall
102.5 cm
Average feels-like high
15.1 °C
Average feels-like low
10.5 °C
Average peak gust
40.5 km/h
Tropical nights (≥ 20 °C)
89 d/yr
Solar radiation
14.6 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.6 °C
since 1940
+0.2 °C per decade · r² = 0.50 · 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
35.1 °C
15 August 2019
Coldest day
-4.9 °C
14 February 1942
Wettest day
201 mm
8 August 1977
Windiest day
93.6 km/h
28 September 1991
Strongest gust
176.4 km/h
28 September 1991
Hottest feels-like
40.9 °C
9 August 2023
Coldest feels-like
-13.0 °C
24 January 2023
Snowiest day
22.0 cm
23 December 2022
Sunniest day
14.0 h
26 May 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 | 7.1 °C | +1.1 °C | 266 mm | +61 mm |
| Feb | 5.7 °C | -0.3 °C | 177 mm | +34 mm |
| Mar | 10.2 °C | +1.4 °C | 131 mm | +1 mm |
| Apr | 14.1 °C | +0.6 °C | 100 mm | -23 mm |
| May | 18.5 °C | +0.6 °C | 128 mm | +8 mm |
| Jun | 23.4 °C | +1.7 °C | 184 mm | +20 mm |
| Jul | 29.3 °C | +3.5 °C | 31 mm | -199 mm |
| Aug | 29.6 °C | +1.6 °C | 351 mm | +191 mm |
| Sep | 27.4 °C | +2.8 °C | 247 mm | +41 mm |
| Oct | 20.7 °C | +1.4 °C | 228 mm | +77 mm |
| Nov | 14.9 °C | +0.7 °C | 158 mm | -21 mm |
| Dec | 10.8 °C | +1.7 °C | 234 mm | -3 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 Oshima?
Oshima has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 14.4 °C and it receives 2,049 mm of precipitation per year.
What is the hottest day ever recorded in Oshima?
The hottest day measured in Oshima between 1940 and 2025 was 15 August 2019, reaching 35.1 °C.
What is the coldest day in Oshima?
The coldest day measured in Oshima between 1940 and 2025 was 14 February 1942, at -4.9 °C.
Does it snow in Oshima?
Yes. Oshima gets on average 102.5 cm of snow per year and has around 9 frost days.
Has the climate of Oshima warmed?
Yes: Oshima warmed by +1.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Oshima?
The wettest day measured in Oshima between 1940 and 2025 was 8 August 1977, with 201 mm of rain in 24 hours.
What was the windiest day in Oshima?
The windiest day measured in Oshima between 1940 and 2025 was 28 September 1991, with winds reaching 93.6 km/h.
What is the warmest month in Oshima?
The warmest month in Oshima is August (26.3 °C on average); the coldest is February (4.2 °C).
How much does it rain in Oshima?
Oshima receives on average 2,049 mm of precipitation per year, spread over about 197 rainy days.
Is it sunny in Oshima?
Oshima 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 Oshima?
The heaviest 24-hour snowfall measured in Oshima between 1940 and 2025 was 23 December 2022, with 22.0 cm.
Are there tropical nights in Oshima?
Yes: Oshima has on average 89 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Oshima?
In Oshima, between 1940 and 2025, the highest apparent temperature reached 40.9 °C on 9 August 2023, and the lowest was -13.0 °C on 24 January 2023.
Compare Oshima with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Oshima