Isogo climate — normals and trends
Isogo (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 15.0 °C and it receives 1,538 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 (26.0 °C on average) and the coldest is January (4.6 °C). Rainfall peaks in September.
Isogo averages 22 frost days, 14 hot days (≥ 30 °C) and 148 rainy days per year.
Isogo has warmed by +2.2 °C between 1940 and 2025, or +0.25 °C per decade. This trend is statistically significant.
The number of frost days there went from about 40 to 4 per year over the period.
The hottest day of the period reached 34.9 °C (on 5 August 2025) and the coldest -11.4 °C (on 6 February 1952).
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
IsogoKanagawa
- coords
- 35.41°, 139.62°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
15.0°C
Average daily high
18.1°C
Average daily low
12.2°C
Annual rainfall
1,538mm
Sunshine / day
8.1h
Mean relative humidity
74%
Average peak wind
18.8km/h
Seasonal range
21.4°C
Frost days (< 0 °C)
22 d/yr
Hot days (≥ 30 °C)
14 d/yr
Rainy days (≥ 1 mm)
148 d/yr
Annual snowfall
25.6 cm
Average feels-like high
17.8 °C
Average feels-like low
10.9 °C
Average peak gust
34.9 km/h
Tropical nights (≥ 20 °C)
84 d/yr
Solar radiation
13.4 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.2 °C
since 1940
+0.3 °C per decade · r² = 0.63 · 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
34.9 °C
5 August 2025
Coldest day
-11.4 °C
6 February 1952
Wettest day
216 mm
26 September 1958
Windiest day
78.9 km/h
1 October 2018
Strongest gust
169.9 km/h
1 October 2018
Hottest feels-like
42.0 °C
10 August 2013
Coldest feels-like
-16.4 °C
6 February 1952
Snowiest day
36.5 cm
12 March 1969
Sunniest day
13.9 h
8 July 2025
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 | 10.5 °C | +2.0 °C | 45 mm | -15 mm |
| Feb | 10.3 °C | +1.4 °C | 23 mm | -51 mm |
| Mar | 14.1 °C | +2.2 °C | 162 mm | +39 mm |
| Apr | 18.3 °C | +1.6 °C | 129 mm | +5 mm |
| May | 21.3 °C | +0.7 °C | 191 mm | +49 mm |
| Jun | 26.5 °C | +3.1 °C | 118 mm | -62 mm |
| Jul | 30.3 °C | +3.3 °C | 51 mm | -105 mm |
| Aug | 31.9 °C | +3.4 °C | 34 mm | -106 mm |
| Sep | 28.7 °C | +3.4 °C | 131 mm | -58 mm |
| Oct | 20.8 °C | +0.6 °C | 142 mm | -46 mm |
| Nov | 16.1 °C | +0.5 °C | 29 mm | -72 mm |
| Dec | 12.5 °C | +1.4 °C | 70 mm | +10 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 Isogo?
Isogo has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 15.0 °C and it receives 1,538 mm of precipitation per year.
What is the hottest day ever recorded in Isogo?
The hottest day measured in Isogo between 1940 and 2025 was 5 August 2025, reaching 34.9 °C.
What is the coldest day in Isogo?
The coldest day measured in Isogo between 1940 and 2025 was 6 February 1952, at -11.4 °C.
Does it snow in Isogo?
Yes. Isogo gets on average 25.6 cm of snow per year and has around 22 frost days.
Has the climate of Isogo warmed?
Yes: Isogo warmed by +2.2 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Isogo?
The wettest day measured in Isogo between 1940 and 2025 was 26 September 1958, with 216 mm of rain in 24 hours.
What was the windiest day in Isogo?
The windiest day measured in Isogo between 1940 and 2025 was 1 October 2018, with winds reaching 78.9 km/h.
What is the warmest month in Isogo?
The warmest month in Isogo is August (26.0 °C on average); the coldest is January (4.6 °C).
How much does it rain in Isogo?
Isogo receives on average 1,538 mm of precipitation per year, spread over about 148 rainy days.
Is it sunny in Isogo?
Isogo gets on average 8.1 hours of sunshine per day, roughly 2,957 hours per year over 1940-2025.
What is the biggest single-day snowfall in Isogo?
The heaviest 24-hour snowfall measured in Isogo between 1940 and 2025 was 12 March 1969, with 36.5 cm.
Are there tropical nights in Isogo?
Yes: Isogo has on average 84 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Isogo?
In Isogo, between 1940 and 2025, the highest apparent temperature reached 42.0 °C on 10 August 2013, and the lowest was -16.4 °C on 6 February 1952.
Compare Isogo with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Isogo