Iwaki climate — normals and trends
Iwaki (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 13.5 °C and it receives 1,549 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 (23.5 °C on average) and the coldest is February (4.4 °C). Rainfall peaks in September.
Iwaki averages 11 frost days, 0 hot days (≥ 30 °C) and 143 rainy days per year.
Iwaki has warmed by +1.4 °C between 1940 and 2025, or +0.17 °C per decade. This trend is statistically significant.
The number of frost days there went from about 19 to 3 per year over the period.
The hottest day of the period reached 31.1 °C (on 30 July 2024) and the coldest -4.8 °C (on 7 February 1984).
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
IwakiFukushima
- coords
- 37.05°, 140.88°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
13.5°C
Average daily high
15.4°C
Average daily low
11.7°C
Annual rainfall
1,549mm
Sunshine / day
8.5h
Mean relative humidity
76%
Average peak wind
24.0km/h
Seasonal range
19.1°C
Frost days (< 0 °C)
11 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
143 d/yr
Annual snowfall
16.5 cm
Average feels-like high
14.2 °C
Average feels-like low
9.2 °C
Average peak gust
37.2 km/h
Tropical nights (≥ 20 °C)
62 d/yr
Solar radiation
14.2 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.4 °C
since 1940
+0.2 °C per decade · r² = 0.33 · 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
31.1 °C
30 July 2024
Coldest day
-4.8 °C
7 February 1984
Wettest day
192 mm
9 October 2004
Windiest day
84.1 km/h
1 October 2002
Strongest gust
139.3 km/h
1 October 2018
Hottest feels-like
37.4 °C
30 July 2024
Coldest feels-like
-12.0 °C
10 January 1940
Snowiest day
24.2 cm
8 February 2014
Sunniest day
14.2 h
13 June 1952
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 | 8.7 °C | +1.8 °C | 64 mm | +5 mm |
| Feb | 7.6 °C | +0.7 °C | 10 mm | -60 mm |
| Mar | 11.2 °C | +1.8 °C | 139 mm | +21 mm |
| Apr | 14.2 °C | +0.9 °C | 132 mm | +2 mm |
| May | 16.9 °C | +0.2 °C | 250 mm | +110 mm |
| Jun | 22.1 °C | +2.8 °C | 165 mm | +4 mm |
| Jul | 25.3 °C | +2.7 °C | 61 mm | -102 mm |
| Aug | 27.1 °C | +2.3 °C | 90 mm | -45 mm |
| Sep | 25.2 °C | +2.5 °C | 144 mm | -60 mm |
| Oct | 19.4 °C | +0.9 °C | 229 mm | +33 mm |
| Nov | 14.8 °C | +0.6 °C | 48 mm | -57 mm |
| Dec | 10.9 °C | +1.4 °C | 105 mm | +35 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 Iwaki?
Iwaki has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 13.5 °C and it receives 1,549 mm of precipitation per year.
What is the hottest day ever recorded in Iwaki?
The hottest day measured in Iwaki between 1940 and 2025 was 30 July 2024, reaching 31.1 °C.
What is the coldest day in Iwaki?
The coldest day measured in Iwaki between 1940 and 2025 was 7 February 1984, at -4.8 °C.
Does it snow in Iwaki?
Yes. Iwaki gets on average 16.5 cm of snow per year and has around 11 frost days.
Has the climate of Iwaki warmed?
Yes: Iwaki warmed by +1.4 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Iwaki?
The wettest day measured in Iwaki between 1940 and 2025 was 9 October 2004, with 192 mm of rain in 24 hours.
What was the windiest day in Iwaki?
The windiest day measured in Iwaki between 1940 and 2025 was 1 October 2002, with winds reaching 84.1 km/h.
What is the warmest month in Iwaki?
The warmest month in Iwaki is August (23.5 °C on average); the coldest is February (4.4 °C).
How much does it rain in Iwaki?
Iwaki receives on average 1,549 mm of precipitation per year, spread over about 143 rainy days.
Is it sunny in Iwaki?
Iwaki gets on average 8.5 hours of sunshine per day, roughly 3,103 hours per year over 1940-2025.
What is the biggest single-day snowfall in Iwaki?
The heaviest 24-hour snowfall measured in Iwaki between 1940 and 2025 was 8 February 2014, with 24.2 cm.
Are there tropical nights in Iwaki?
Yes: Iwaki has on average 62 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Iwaki?
In Iwaki, between 1940 and 2025, the highest apparent temperature reached 37.4 °C on 30 July 2024, and the lowest was -12.0 °C on 10 January 1940.
Compare Iwaki with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Iwaki