Cool
Average highs are around 19°C, so pack for cooler days.
September verdict
Karuizawa, Japan in September
Weather score25Poor
Poor for holiday weather
Average highs are around 19°C, so pack for cooler days. Sunshine averages 3.7h per day, so this is not one of the brighter months. Rainfall averages 210mm, so showers are a real planning factor.
September weather
Monthly averages
Temp
19°C
Rain
210mm
Sun
3.7h
Weather score
25
Poor
Seasonal climate calendar
TemperatureTemp
RainRain
SunSun
Weather scoreWeather score
Trip feel
Wet
Rainfall averages 210mm, so showers are a real planning factor.
Limited sun
Sunshine averages 3.7h per day, so this is not one of the brighter months.
Map
Weather map
Compare Karuizawa, Japan with nearby places by weather score, rain, sun, temperature, and swim conditions.
Temperature
September19°C average high
September sits in the warmer part of the year, so midday sightseeing can feel heavier than in cooler months.
Warmest monthsJune to September
This stretch sets the upper range for average daytime heat.
Rain
September210mm average rain
September is one of Karuizawa's wettest months, so rain is likely to be a major planning factor.
Driest monthsJanuary to March and November to December
This is the drier part of the year, when outdoor plans usually need less weather flexibility.
Sun
September3.7 hours average sun
September is one of Karuizawa's cloudier months, so sunshine-led plans are less reliable.
Brightest monthsMarch to May
This stretch has the strongest sunshine in the monthly averages.
Weather score
September25 weather score
September scores below Karuizawa's yearly average, so the weather trade-offs are more noticeable.
Best weather monthsJuly to August
These months have the strongest weather score in the monthly averages.
