Iida climate — normals and trends
Iida (Japan) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 9.3 °C and it receives 2,197 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 (21.6 °C on average) and the coldest is January (-4.2 °C). Rainfall peaks in July.
Iida averages 123 frost days, 3 hot days (≥ 30 °C) and 177 rainy days per year.
Iida has warmed by +3.3 °C between 1940 and 2025, or +0.39 °C per decade. This trend is statistically significant.
The number of frost days there went from about 144 to 102 per year over the period.
The hottest day of the period reached 33.7 °C (on 23 July 2018) and the coldest -25.0 °C (on 21 December 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
IidaNagano
- coords
- 35.52°, 137.82°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.3°C
Average daily high
14.0°C
Average daily low
4.9°C
Annual rainfall
2,197mm
Sunshine / day
8.5h
Mean relative humidity
76%
Average peak wind
9.8km/h
Seasonal range
25.8°C
Frost days (< 0 °C)
123 d/yr
Hot days (≥ 30 °C)
3 d/yr
Rainy days (≥ 1 mm)
177 d/yr
Annual snowfall
123.6 cm
Average feels-like high
12.9 °C
Average feels-like low
3.3 °C
Average peak gust
39.7 km/h
Tropical nights (≥ 20 °C)
8 d/yr
Solar radiation
14.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+3.3 °C
since 1940
+0.4 °C per decade · r² = 0.68 · 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
33.7 °C
23 July 2018
Coldest day
-25.0 °C
21 December 1947
Wettest day
183 mm
26 August 1962
Windiest day
45.6 km/h
26 September 1959
Strongest gust
219.2 km/h
26 September 1959
Hottest feels-like
38.3 °C
30 July 2025
Coldest feels-like
-29.5 °C
4 January 1958
Snowiest day
31.3 cm
15 February 2014
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 | 2.3 °C | +1.2 °C | 74 mm | -16 mm |
| Feb | 0.8 °C | -1.5 °C | 75 mm | -28 mm |
| Mar | 8.9 °C | +2.3 °C | 197 mm | +37 mm |
| Apr | 15.5 °C | +2.1 °C | 118 mm | -62 mm |
| May | 19.2 °C | +1.0 °C | 237 mm | +36 mm |
| Jun | 24.1 °C | +2.9 °C | 276 mm | -18 mm |
| Jul | 28.6 °C | +3.8 °C | 191 mm | -130 mm |
| Aug | 28.4 °C | +2.3 °C | 194 mm | -18 mm |
| Sep | 25.4 °C | +2.9 °C | 262 mm | +21 mm |
| Oct | 18.3 °C | +1.4 °C | 185 mm | +2 mm |
| Nov | 11.1 °C | +0.1 °C | 61 mm | -61 mm |
| Dec | 6.2 °C | +1.8 °C | 96 mm | +4 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 Iida?
Iida has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 9.3 °C and it receives 2,197 mm of precipitation per year.
What is the hottest day ever recorded in Iida?
The hottest day measured in Iida between 1940 and 2025 was 23 July 2018, reaching 33.7 °C.
What is the coldest day in Iida?
The coldest day measured in Iida between 1940 and 2025 was 21 December 1947, at -25.0 °C.
Does it snow in Iida?
Yes. Iida gets on average 123.6 cm of snow per year and has around 123 frost days.
Has the climate of Iida warmed?
Yes: Iida warmed by +3.3 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Iida?
The wettest day measured in Iida between 1940 and 2025 was 26 August 1962, with 183 mm of rain in 24 hours.
What was the windiest day in Iida?
The windiest day measured in Iida between 1940 and 2025 was 26 September 1959, with winds reaching 45.6 km/h.
What is the warmest month in Iida?
The warmest month in Iida is August (21.6 °C on average); the coldest is January (-4.2 °C).
How much does it rain in Iida?
Iida receives on average 2,197 mm of precipitation per year, spread over about 177 rainy days.
Is it sunny in Iida?
Iida 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 Iida?
The heaviest 24-hour snowfall measured in Iida between 1940 and 2025 was 15 February 2014, with 31.3 cm.
Are there tropical nights in Iida?
Yes: Iida has on average 8 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Iida?
In Iida, between 1940 and 2025, the highest apparent temperature reached 38.3 °C on 30 July 2025, and the lowest was -29.5 °C on 4 January 1958.
Compare Iida with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Iida