Tsuyu ( the rainy season, つゆ or 梅雨) is officially over in most parts of Japan according to the Japan Meteorological Agency (JMA). The hot summer of 2012 has begun.
On the morning of July 17, 2012, JMA announced that the tsuyu rainy season is over in most parts of Japan:
Shikoku (Kochi, Kagawa, Ehime, Tokushima)
Shikoku (Hiroshima, Okayama, Yamaguchi, Shimane, Tottori)
Kinki (Hyogo, Kobe, Osaka, Nara, Kyoto, Wakayama)
Tokai (Aichi, Nagoya, Gifu, Mie)
Hokuriku (Fukui, Ishikawa, Toyama) - July 18, 2012
Koshinetsu (Nagano, Yamanashi, Niigata)
Kanto (Tokyo, Kanagawa, Chiba, Saitama, Gunma, Tochigi)
Tohoku and Hokkaido haven't finished their rainy season yet, but temperatures are already rising over 30 C (86 F) with over 60~80% humidity.
If you travel in Japan, be prepared against heat stroke.