Iyo climate — normals and trends
Iyo (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 14.9 °C and it receives 1,680 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 (26.1 °C on average) and the coldest is January (4.1 °C). Rainfall peaks in June.
Iyo averages 23 frost days, 24 hot days (≥ 30 °C) and 157 rainy days per year.
Iyo 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 40 to 6 per year over the period.
The hottest day of the period reached 34.2 °C (on 10 August 1990) and the coldest -10.9 °C (on 19 February 1977).
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
IyoEhime
- coords
- 33.75°, 132.70°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
14.9°C
Average daily high
18.4°C
Average daily low
11.7°C
Annual rainfall
1,680mm
Sunshine / day
8.9h
Mean relative humidity
76%
Average peak wind
13.1km/h
Seasonal range
22.0°C
Frost days (< 0 °C)
23 d/yr
Hot days (≥ 30 °C)
24 d/yr
Rainy days (≥ 1 mm)
157 d/yr
Annual snowfall
22.5 cm
Average feels-like high
18.5 °C
Average feels-like low
11.0 °C
Average peak gust
37.2 km/h
Tropical nights (≥ 20 °C)
84 d/yr
Solar radiation
15.1 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.5 °C
since 1940
+0.3 °C per decade · r² = 0.72 · 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
34.2 °C
10 August 1990
Coldest day
-10.9 °C
19 February 1977
Wettest day
160 mm
4 July 1969
Windiest day
59.1 km/h
7 September 2004
Strongest gust
182.9 km/h
7 September 2004
Hottest feels-like
40.4 °C
3 August 2024
Coldest feels-like
-14.9 °C
19 February 1977
Snowiest day
24.0 cm
15 February 1968
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 | 7.6 °C | +0.3 °C | 48 mm | -21 mm |
| Feb | 6.6 °C | -1.6 °C | 59 mm | -23 mm |
| Mar | 13.5 °C | +1.5 °C | 115 mm | +6 mm |
| Apr | 18.0 °C | +0.7 °C | 99 mm | -36 mm |
| May | 21.5 °C | +0.1 °C | 254 mm | +96 mm |
| Jun | 26.3 °C | +1.9 °C | 334 mm | +78 mm |
| Jul | 30.9 °C | +2.7 °C | 64 mm | -170 mm |
| Aug | 30.8 °C | +1.5 °C | 176 mm | +9 mm |
| Sep | 28.6 °C | +2.5 °C | 215 mm | +21 mm |
| Oct | 23.4 °C | +2.5 °C | 173 mm | +50 mm |
| Nov | 16.5 °C | +0.9 °C | 43 mm | -43 mm |
| Dec | 11.7 °C | +1.6 °C | 44 mm | -25 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 Iyo?
Iyo has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 14.9 °C and it receives 1,680 mm of precipitation per year.
What is the hottest day ever recorded in Iyo?
The hottest day measured in Iyo between 1940 and 2025 was 10 August 1990, reaching 34.2 °C.
What is the coldest day in Iyo?
The coldest day measured in Iyo between 1940 and 2025 was 19 February 1977, at -10.9 °C.
Does it snow in Iyo?
Yes. Iyo gets on average 22.5 cm of snow per year and has around 23 frost days.
Has the climate of Iyo warmed?
Yes: Iyo warmed by +2.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Iyo?
The wettest day measured in Iyo between 1940 and 2025 was 4 July 1969, with 160 mm of rain in 24 hours.
What was the windiest day in Iyo?
The windiest day measured in Iyo between 1940 and 2025 was 7 September 2004, with winds reaching 59.1 km/h.
What is the warmest month in Iyo?
The warmest month in Iyo is August (26.1 °C on average); the coldest is January (4.1 °C).
How much does it rain in Iyo?
Iyo receives on average 1,680 mm of precipitation per year, spread over about 157 rainy days.
Is it sunny in Iyo?
Iyo gets on average 8.9 hours of sunshine per day, roughly 3,249 hours per year over 1940-2025.
What is the biggest single-day snowfall in Iyo?
The heaviest 24-hour snowfall measured in Iyo between 1940 and 2025 was 15 February 1968, with 24.0 cm.
Are there tropical nights in Iyo?
Yes: Iyo has on average 84 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Iyo?
In Iyo, between 1940 and 2025, the highest apparent temperature reached 40.4 °C on 3 August 2024, and the lowest was -14.9 °C on 19 February 1977.
Compare Iyo with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Iyo