Aioi climate — normals and trends
Aioi (Japan) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 15.8 °C and it receives 1,500 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 (26.4 °C on average) and the coldest is January (6.2 °C). Rainfall peaks in September.
Aioi averages 1 frost days, 3 hot days (≥ 30 °C) and 124 rainy days per year.
Aioi has warmed by +1.0 °C between 1940 and 2025, or +0.12 °C per decade. This trend is statistically significant.
The hottest day of the period reached 32.4 °C (on 9 August 2006) and the coldest -2.8 °C (on 26 February 1981).
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
AioiHyōgo
- coords
- 34.80°, 134.47°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
15.8°C
Average daily high
17.8°C
Average daily low
13.9°C
Annual rainfall
1,500mm
Sunshine / day
9.1h
Mean relative humidity
75%
Average peak wind
22.8km/h
Seasonal range
20.2°C
Frost days (< 0 °C)
1 d/yr
Hot days (≥ 30 °C)
3 d/yr
Rainy days (≥ 1 mm)
124 d/yr
Annual snowfall
3.5 cm
Average feels-like high
17.4 °C
Average feels-like low
12.3 °C
Average peak gust
35.7 km/h
Tropical nights (≥ 20 °C)
100 d/yr
Solar radiation
15.4 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.0 °C
since 1940
+0.1 °C per decade · r² = 0.43 · 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
32.4 °C
9 August 2006
Coldest day
-2.8 °C
26 February 1981
Wettest day
240 mm
27 October 1961
Windiest day
85.2 km/h
27 September 1991
Strongest gust
152.3 km/h
4 September 1993
Hottest feels-like
38.9 °C
24 July 2018
Coldest feels-like
-12.0 °C
26 February 1981
Snowiest day
12.5 cm
12 February 1994
Sunniest day
14.0 h
21 May 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 | 8.4 °C | 0.0 °C | 17 mm | -33 mm |
| Feb | 7.0 °C | -1.8 °C | 27 mm | -38 mm |
| Mar | 10.7 °C | -0.9 °C | 107 mm | +3 mm |
| Apr | 15.3 °C | -0.5 °C | 58 mm | -76 mm |
| May | 19.2 °C | 0.0 °C | 191 mm | +38 mm |
| Jun | 23.7 °C | +1.3 °C | 226 mm | +22 mm |
| Jul | 28.2 °C | +2.0 °C | 64 mm | -127 mm |
| Aug | 29.7 °C | +1.8 °C | 126 mm | -3 mm |
| Sep | 27.8 °C | +2.2 °C | 281 mm | +75 mm |
| Oct | 22.7 °C | +1.9 °C | 224 mm | +89 mm |
| Nov | 16.4 °C | +0.5 °C | 30 mm | -51 mm |
| Dec | 11.9 °C | +0.9 °C | 36 mm | -13 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 Aioi?
Aioi has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 15.8 °C and it receives 1,500 mm of precipitation per year.
What is the hottest day ever recorded in Aioi?
The hottest day measured in Aioi between 1940 and 2025 was 9 August 2006, reaching 32.4 °C.
What is the coldest day in Aioi?
The coldest day measured in Aioi between 1940 and 2025 was 26 February 1981, at -2.8 °C.
Does it snow in Aioi?
Yes. Aioi gets on average 3.5 cm of snow per year and has around 1 frost days.
Has the climate of Aioi warmed?
Yes: Aioi warmed by +1.0 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Aioi?
The wettest day measured in Aioi between 1940 and 2025 was 27 October 1961, with 240 mm of rain in 24 hours.
What was the windiest day in Aioi?
The windiest day measured in Aioi between 1940 and 2025 was 27 September 1991, with winds reaching 85.2 km/h.
What is the warmest month in Aioi?
The warmest month in Aioi is August (26.4 °C on average); the coldest is January (6.2 °C).
How much does it rain in Aioi?
Aioi receives on average 1,500 mm of precipitation per year, spread over about 124 rainy days.
Is it sunny in Aioi?
Aioi gets on average 9.1 hours of sunshine per day, roughly 3,322 hours per year over 1940-2025.
What is the biggest single-day snowfall in Aioi?
The heaviest 24-hour snowfall measured in Aioi between 1940 and 2025 was 12 February 1994, with 12.5 cm.
Are there tropical nights in Aioi?
Yes: Aioi has on average 100 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Aioi?
In Aioi, between 1940 and 2025, the highest apparent temperature reached 38.9 °C on 24 July 2018, and the lowest was -12.0 °C on 26 February 1981.
Compare Aioi with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Aioi