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Koyasan

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Koyasan Weather, Climate and Best Time to Visit

Data source:Meteostat
Update date:2025-09

Koyasan year round climate

  • Spring (March–May): Average 10.6–18.6°C, mild and comfortable climate, but with relatively high rainfall, especially in May. Common activities: Visiting Koyasan temples, hiking (be aware of changing weather conditions). Recommended clothing: Light jacket, long-sleeved shirt, rain gear.
  • Summer (June–August): Average 22.6–28.7°C, hot and humid, with occasional showers. Common activities: Visiting temples, experiencing local culture, escaping the heat in the mountains. Recommended clothing: Breathable and sweat-wicking clothing, sun hat, rain gear.
  • Autumn (September–November): Average 15.7–27.0°C, comfortable and pleasant climate, with reduced rainfall. Common activities: Autumn leaves viewing (in some areas), visiting temples, hiking. Recommended clothing: Light jacket, long-sleeved shirt.
  • Winter (December–February): Average 7.2–9.8°C, cold and dry, with little rain. Common activities: Visiting temples, experiencing onsen (in nearby areas). Recommended clothing: Warm jacket, sweater, scarf, gloves.

Koyasan climatological average

Annual average temperature: approx. 17.6°C / Annual rainfall: approx. 1794 mm / Summer humidity: 70%–80% / Rainiest month: May

Koyasan monthly average temperature and precipitation

Month
Air temperature (°C)
Precipitation (mm)
January
7.2°C
63.9
February
7.2°C
59.2
March
10.6°C
113.6
April
15.4°C
163.5
May
18.6°C
313.2
June
22.6°C
285.1
July
27.4°C
200.3
August
28.7°C
130.6
September
27°C
161.5
October
20.5°C
141
November
15.7°C
101.2
December
9.8°C
61.5

Koyasan weather for the next seven days

4/27
Monday
Heavy rain
18.5°C/10.7°C
4/28
Tuesday
Patchy rain nearby
23.6°C/10.4°C
4/29
Wednesday
Patchy rain nearby
15.8°C/10.9°C
4/30
Thursday
Patchy rain nearby
16.6°C/9.7°C
5/1
Friday
Moderate rain
13.3°C/6.8°C
5/2
Saturday
Sunny
21.2°C/6.9°C
5/3
Sunday
Patchy rain nearby
20.6°C/11.5°C