The best time to visit Hokkaido & Northern Japan (Sapporo) is Jun–Aug. Month by month, the verdicts rate May–Aug as comfortable on both daytime heat and rainfall — 4 months in all.
Snowy winters; escapes the rainy season
| Month | High °C | High °F | Rainy days | Verdict |
|---|---|---|---|---|
| January | -4.1 | 25 | 79% | Too cold |
| February | -3.6 | 26 | 73% | Too cold |
| March | -0.2 | 32 | 52% | Too cold |
| April | 7.9 | 46 | 38% | Fair |
| May | 15.0 | 59 | 36% | Go |
| June | 19.6 | 67 | 34% | Go |
| July | 23.4 | 74 | 40% | Go |
| August | 24.2 | 76 | 43% | Go |
| September | 20.1 | 68 | 51% | Fair |
| October | 13.5 | 56 | 53% | Fair |
| November | 5.3 | 42 | 66% | Too wet |
| December | -1.9 | 29 | 76% | Too cold |
Verdict combines mean daytime high with rainy-day frequency. “Rainy days” is the share of days in the month with at least 1 mm of rain.
June is the driest month, with rain on 34% of days and daytime highs near 19.6°C (67°F). January is the wettest, at 79%. Temperature swings hard across the year — 28.3°C between August (24.2°C / 76°F) and January (-4.1°C / 25°F) — so packing for the wrong month is the main risk. The record rules out too cold in Dec–Mar; too wet in November.