Karuizawa Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Karuizawa.
Climate overview of Karuizawa
Temperatures in Karuizawa, Nagano Prefecture, Japan, vary greatly throughout the year. August is the hottest month at 28°C (82°F), while January is the coldest at 4°C (39°F).
The city receives considerable rain/snowfall, with around 1785 mm (70 in) annually. July is the wettest month. It has a distinct rainy season from June to October, with warm summers and cold winters. May is the sunniest month, averaging 7.0 hours of sunshine per day.
Karuizawa Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Karuizawa - and find the best time to visit.
Monthly Temperature in Karuizawa
The climate in Karuizawa is known for significant temperature differences throughout the year, making the weather dynamic. Typically, average maximum daytime temperatures range from a comfortable 28°C (82°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 -5°C (23°F) during the colder months.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Karuizawa
Karuizawa has a notably wet climate with abundant precipitation, recording 1785 mm (70 in) of rain/snowfall per year. The climate in Karuizawa shows significant variation throughout the year. Expect heavy rainfall in July, the wettest month, with an average of 255 mm (10 in) of precipitation over 23 rainy days.
In contrast, the driest month December offers drier and sunnier days, with around 63 mm (2.5 in) of snow/rainfall over 15 snowy/rainy days. For more details, please visit our Karuizawa 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 Karuizawa
Karuizawa offers a pleasant mix of sunny and slightly overcast days. The difference in sunshine hours between May (7.0 hours daily) and January (4.3 hours daily) provides a bit of variety for visitors and residents.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Humidity in Karuizawa by Month
The relative humidity is high throughout the year in Karuizawa.
The city experiences its highest humidity in January, reaching 78%. In April, the humidity drops to its lowest level at 61%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit Karuizawa
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: May
- Warmest weather: July and August
- Most sunshine: May and August
- Fewer rainy days: April, May, October, 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 -5°C (23°F).
Frequently asked questions about the climate in Karuizawa
What is the best time to visit Karuizawa?
May typically offers the most optimal weather in Karuizawa. In contrast, January, February, March and December tend to have less optimal conditions. Karuizawa has a distinct rainy season from June to October, with warm summers and cold winters.
What temperatures can I expect in Karuizawa?
Daytime highs range from 4°C (39°F) in January to 28°C (82°F) in August. Nighttime lows range from -5°C (23°F) to 19°C (66°F). Temperatures vary considerably through the year.
How much rain does Karuizawa get?
Annual rainfall is around 1785 mm (70 in). July is the wettest month with 255 mm (10 in), while December is the driest with 63 mm (2.5 in).
How sunny is Karuizawa?
Karuizawa receives around 1,951 hours of sunshine per year. May is the sunniest month with 209 hours, while January is the cloudiest with just 128 hours.
Karuizawa 3-Day Forecast
Karuizawa on the map
Karuizawa is highlighted - select any city to see its climate.
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