Isa climate — normals and trends
Isa (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 16.3 °C and it receives 2,195 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 (26.6 °C on average) and the coldest is January (6.0 °C). Rainfall peaks in June.
Isa averages 12 frost days, 40 hot days (≥ 30 °C) and 160 rainy days per year.
Isa has warmed by +2.5 °C between 1940 and 2025, or +0.29 °C per decade. This trend is statistically significant.
The number of frost days there went from about 20 to 4 per year over the period.
The hottest day of the period reached 35.8 °C (on 17 July 1994) and the coldest -8.4 °C (on 10 February 1980).
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
IsaKagoshima
- coords
- 32.07°, 130.61°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
16.3°C
Average daily high
20.3°C
Average daily low
12.9°C
Annual rainfall
2,195mm
Sunshine / day
8.0h
Mean relative humidity
77%
Average peak wind
13.4km/h
Seasonal range
20.6°C
Frost days (< 0 °C)
12 d/yr
Hot days (≥ 30 °C)
40 d/yr
Rainy days (≥ 1 mm)
160 d/yr
Annual snowfall
4.6 cm
Average feels-like high
20.8 °C
Average feels-like low
12.5 °C
Average peak gust
37.1 km/h
Tropical nights (≥ 20 °C)
97 d/yr
Solar radiation
14.0 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.5 °C
since 1940
+0.3 °C per decade · r² = 0.75 · 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
35.8 °C
17 July 1994
Coldest day
-8.4 °C
10 February 1980
Wettest day
245 mm
19 July 1976
Windiest day
62.9 km/h
27 September 1991
Strongest gust
181.4 km/h
27 September 1991
Hottest feels-like
43.2 °C
17 July 1994
Coldest feels-like
-12.9 °C
10 February 1980
Snowiest day
10.9 cm
23 January 1998
Sunniest day
13.7 h
15 June 1956
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 | 10.3 °C | +0.5 °C | 48 mm | -28 mm |
| Feb | 9.6 °C | -1.4 °C | 69 mm | -33 mm |
| Mar | 15.6 °C | +1.1 °C | 154 mm | +8 mm |
| Apr | 19.9 °C | +0.7 °C | 136 mm | -49 mm |
| May | 23.0 °C | 0.0 °C | 366 mm | +136 mm |
| Jun | 27.7 °C | +2.2 °C | 380 mm | -81 mm |
| Jul | 31.6 °C | +2.4 °C | 67 mm | -260 mm |
| Aug | 31.4 °C | +1.1 °C | 307 mm | +113 mm |
| Sep | 30.2 °C | +2.4 °C | 158 mm | -35 mm |
| Oct | 26.4 °C | +3.3 °C | 129 mm | +19 mm |
| Nov | 18.5 °C | +0.8 °C | 48 mm | -46 mm |
| Dec | 14.2 °C | +2.0 °C | 53 mm | -23 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 Isa?
Isa has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 16.3 °C and it receives 2,195 mm of precipitation per year.
What is the hottest day ever recorded in Isa?
The hottest day measured in Isa between 1940 and 2025 was 17 July 1994, reaching 35.8 °C.
What is the coldest day in Isa?
The coldest day measured in Isa between 1940 and 2025 was 10 February 1980, at -8.4 °C.
Does it snow in Isa?
Yes. Isa gets on average 4.6 cm of snow per year and has around 12 frost days.
Has the climate of Isa warmed?
Yes: Isa warmed by +2.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Isa?
The wettest day measured in Isa between 1940 and 2025 was 19 July 1976, with 245 mm of rain in 24 hours.
What was the windiest day in Isa?
The windiest day measured in Isa between 1940 and 2025 was 27 September 1991, with winds reaching 62.9 km/h.
What is the warmest month in Isa?
The warmest month in Isa is August (26.6 °C on average); the coldest is January (6.0 °C).
How much does it rain in Isa?
Isa receives on average 2,195 mm of precipitation per year, spread over about 160 rainy days.
Is it sunny in Isa?
Isa gets on average 8.0 hours of sunshine per day, roughly 2,920 hours per year over 1940-2025.
What is the biggest single-day snowfall in Isa?
The heaviest 24-hour snowfall measured in Isa between 1940 and 2025 was 23 January 1998, with 10.9 cm.
Are there tropical nights in Isa?
Yes: Isa has on average 97 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Isa?
In Isa, between 1940 and 2025, the highest apparent temperature reached 43.2 °C on 17 July 1994, and the lowest was -12.9 °C on 10 February 1980.
Compare Isa with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Isa