Although the level of rain and the timing can vary year on year, and geographically by area of Japan, it can result in continuous heavy rain from mid-June to mid-July over the Japanese archipelago.

The rainy season in Japan, known as "Tsuyu" or "Baiu," is usually not "bad" in the sense of constant torrential downpours, but it can be persistent, grey, and very humid. It typically lasts from early June to mid-July for most of the country (excluding Hokkaido, which remains relatively dry). During this time, you can expect frequent light to moderate rain, overcast skies, and high humidity levels that can make temperatures in the mid-20s°C feel much hotter. While it rarely rains all day every day, the "dampness" can be a nuisance for outdoor sightseeing. However, there are significant upsides: the famous hydrangeas (ajisai) are in full bloom, Japanese gardens look exceptionally lush and beautiful in the rain, and major tourist sites like Kyoto or Hakone are often much less crowded. Prices for hotels can also be lower. If you prepare with a good umbrella, waterproof shoes, and a flexible itinerary that includes indoor activities like museums or department stores, the rainy season can actually be a peaceful and poetic time to visit. Just be wary of the "Typhoon Season" that follows in late summer, which brings much more severe weather.