Chase the autumn leaves in Japan
Japan is one of these cases which turns into a gold, yellow and orange fairy tale starting from September. And we can honestly say: We cannot imagine a more beautiful season to visit Japan.
Koshu Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Koshu.
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Climate overview of Koshu
Koshu, Yamanashi, Japan, experiences significant temperature variation throughout the year. Summers bring daytime highs of 27°C (81°F) in August, while winters cool to 4°C (39°F) in January.
The city receives considerable rain/snowfall, with around 1869 mm (74 in) annually. September is the wettest month. It has a distinct rainy season from June to October, with warm summers and cold winters. The most sunshine falls in August, with an average of 6.7 hours of daily sunshine.
Koshu Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Koshu - and find the best time to visit.
Monthly Temperature in Koshu
Depending on the time of the year, temperatures range from comfortable to chilly in Koshu. Typically, average maximum daytime temperatures range from a comfortable 27°C (81°F) in August to a chilly 4°C (39°F) in the coolest month, January.
Nights vary from 19°C (66°F) in August to around -6°C (21°F) during the colder months.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Koshu
Koshu has a relatively rain/snowy climate with high precipitation levels, averaging 1869 mm (74 in) of rain/snowfall annually. The climate in Koshu shows significant variation throughout the year. Expect heavy rainfall in September, the wettest month, with an average of 240 mm (9.4 in) of precipitation over 19 rainy days.
In contrast, the driest month December offers drier and sunnier days, with around 66 mm (2.6 in) of snow/rainfall over 10 snowy/rainy days. For more details, please visit our Koshu Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Koshu
Koshu offers a pleasant mix of sunny and slightly overcast days. The difference in sunshine hours between August (6.7 hours daily) and June (5.0 hours daily) provides a bit of variety for visitors and residents.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Data from: Yamanashi, Japan (4 KM, 2 Miles).
Daily hours of sunshine
Data from: Yamanashi, Japan (4 KM, 2 Miles).
Humidity in Koshu by Month
The relative humidity is high throughout the year in Koshu.
The city experiences its highest humidity in July, reaching 74%. In March, the humidity drops to its lowest level at 59%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Data from: Yamanashi, Japan (4 KM, 2 Miles).
Best Time to Visit Koshu
The most comfortable overall weather for exploring Koshu is usually found in May. Conditions are generally least comfortable in January, February, March, October and December.
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
Jan
cold
Feb
cold
Mar
wet
Apr
mixed
May
very good
Jun
mixed
Jul
mixed
Aug
good
Sep
mixed
Oct
very wet
Nov
mixed
Dec
cold
- Best overall: May
- Warmest weather: July and August
- Most sunshine: April, May and August
- Fewest rainy days: January, November and December
- Seasonal pattern: A distinct rainy season from June to October, with warm summers and cold winters
- Coldest conditions: January, with freezing nights around -6°C (21°F).
Frequently asked questions about the climate in Koshu
What is the best time to visit Koshu?
May typically offers the most optimal weather in Koshu. In contrast, January, February, March, October and December tend to have less optimal conditions. Koshu has a distinct rainy season from June to October, with warm summers and cold winters.
What temperatures can I expect in Koshu?
Daytime highs range from 4°C (39°F) in January to 27°C (81°F) in August. Nighttime lows range from -6°C (21°F) to 19°C (66°F). Temperatures vary considerably through the year.
How much rain does Koshu get?
Annual rainfall is around 1869 mm (74 in). September is the wettest month with 240 mm (9.4 in), while December is the driest with 66 mm (2.6 in).
How sunny is Koshu?
Koshu receives around 2,097 hours of sunshine per year. August is the sunniest month with 201 hours, while June is the cloudiest with just 150 hours. Overall, Koshu enjoys abundant sunshine.
Koshu 3-Day Forecast
Koshu on the map
Koshu is highlighted - select any city to see its climate.
Popular in October
Where to go in October - average daytime high across popular destinations.
Naha
28°C (82°F) Osaka
24°C (75°F) Kyoto23°C (73°F) Tokyo23°C (73°F) Hakone21°C (70°F) Hakuba17°C (63°F) Sapporo16°C (61°F) Niseko15°C (59°F) Bucket list
Need travel inspiration? Check out our bucket list articles and be inspired.
Chase the autumn leaves in Japan
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