SeasonMapKaruizawa weather by month
Japan
The best time to visit Karuizawa is May, June and September — 79/100 in May, 19°C and 16 rainy days. The best season is summer, June to August (74/100 on average).
The worst month is January at 51/100 — freezing, a little rain, clean air. See January →
Updated September 2026 · climate normals from ERA5 reanalysis
Planning the wider trip? Best time to visit Japan →
Karuizawa, month by month
Comfort score out of 100 for the kind of trip Karuizawa is best for, the average high, rainy days and hours of sun a day from the climate normals, and how busy it tends to be.
| Month | Score | Tier | High | Rain | Sun | Crowds | On |
|---|---|---|---|---|---|---|---|
| JanJanuary | 51 | D | 3°C | 7 d | 8 h | Busy | 2 |
| FebFebruary | 54 | D | 4°C | 8 d | 9 h | Quiet | 2 |
| MarMarch | 63 | C | 9°C | 12 d | 9 h | Busy | 1 |
| AprApril | 73 | B | 14°C | 13 d | 9 h | Busy | — |
| MayMay | 79 | B | 19°C | 16 d | 9 h | Busy | — |
| JunJune | 77 | B | 21°C | 20 d | 9 h | Busy | 1 |
| JulJuly | 71 | B | 25°C | 23 d | 9 h | Peak | 2 |
| AugAugust | 75 | B | 26°C | 22 d | 10 h | Peak | 2 |
| SepSeptember | 78 | B | 21°C | 21 d | 8 h | Busy | — |
| OctOctober | 66 | C | 15°C | 14 d | 7 h | Shoulder | 1 |
| NovNovember | 69 | C | 11°C | 7 d | 8 h | Shoulder | 2 |
| DecDecember | 58 | D | 6°C | 8 d | 8 h | Busy | 1 |
What's on in Karuizawa through the year
Festivals, natural spectacles, holidays and the seasons to watch out for — curated and sourced. The month pages carry the detail.
Crowds in Karuizawa in May
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.
BusyGolden Week in Japan(estimated)
Peak crowdsBusyShoulder seasonQuiet