If you don't have a car rental in Japan and want to visit Mount Koya, I recommend this itinerary. It can serve as an introduction to your next trip. Dining options are readily available. Try to go on a weekday when there are fewer tourists and it should be more peaceful.
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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
4/10
Friday
Heavy rain
19.4°C/13°C
4/11
Saturday
Patchy rain nearby
17.8°C/8.6°C
4/12
Sunday
Partly Cloudy
19.4°C/7.1°C
4/13
Monday
Partly Cloudy
21.6°C/10.9°C
4/14
Tuesday
Partly Cloudy
21.3°C/12.1°C
4/15
Wednesday
Patchy rain nearby
14.8°C/13.2°C
4/16
Thursday
Patchy rain nearby
19.9°C/11°C
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