SeasonMapKaruizawa weather in August
Japan
August in Karuizawa: hot, soaked, with clean air — fine if you can take 22 rainy days.
#4 of 12 months in Karuizawa · #802 of 1383 destinations to visit in August · comfort 75/100 (tier B)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Karuizawa in August
Other months in Karuizawa
Karuizawa's forum calls May one of the most pleasant months — its elevation keeps it noticeably cooler than Tokyo, with a day-to-night temperature swing of around 10°C that catches some visitors out. Regulars recommend layers for exactly that reason, plus a rain jacket just in case, and flag the first week of May (Golden Week) as considerably busier than the rest of the month.
Add your own note from Karuizawa's card on the map.
Karuizawa climate normals — August
| Daytime high | 26°C / 78°F | 🥵 hot |
|---|---|---|
| Nighttime low | 17°C / 63°F | |
| Feels like (high) | 29°C / 84°F | |
| Rainfall | 195 mm / 7.7 in | ⛈ soaked |
| Rainy days | 22 days | |
| Humidity | 85% | 💦 very humid |
| Dew point | 20°C / 67°F | |
| Sunshine | 9.8 h/day | |
| Daylight | 13.5 h | |
| Wind | 8 km/h / 5 mph | |
| Air quality (US AQI) | 46 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Karuizawa in August
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Peak crowdsSummer season, Obon, Summer break (natsuyasumi) in Japan(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Karuizawa's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherKaruizawa's best weather comes in May, June and September — separate windows, not one continuous season.
Best weatherFair weatherToughest weather
What's on in Karuizawa in August
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
Summer season
15 Jul – 31 AugCrowdedBook earlyTokyo's hot-weather escape since the 1880s, and the population multiplies for six weeks. Restaurants need booking, the outlet mall is full, and the expressway backs up on Friday evenings.
- Holiday
Obon
13–16 AugNational holidayCrowdedThe peak of the peak. Second homes are all occupied, the bicycle lanes are busy, and a table anywhere decent needs to have been booked in spring. Source ↗
Nearby, and something's on
Within 300 km of Karuizawa — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Karuizawa?
Karuizawa in August — FAQ
- Is August a good time to visit Karuizawa?
- August in Karuizawa: hot, soaked, with clean air — fine if you can take 22 rainy days. It ranks #4 of 12 months for Karuizawa on SeasonMap's comfort score (75/100).
- What is the weather like in Karuizawa in August?
- In August, Karuizawa averages a daily high of 25.7°C and a low of 17°C, with about 194.9 mm of rain over roughly 22.2 rainy days.
- What is the air quality in Karuizawa in August?
- Karuizawa has a mean US Air Quality Index of about 46 in August.
Other months in Karuizawa
Compare Karuizawa in August
Warmer or cooler than Karuizawa in August
Similar destinations in East Asia — August
Within 300 km: Matsumoto's Kamikochi open season around 17 Apr – 15 Nov, and Hakuba's High trails and huts open around 1 Jul – 15 Oct.