Summer in Japan. Summer in Japan lasts from about June to mid-September, depending on the location. Summers are hot and humid, with temperatures ranging from approximately 70 to 90 °F (21 to 32 °C).

In July, Japan is in the heart of summer, characterized by intense heat and extreme humidity. This is primarily caused by the Pacific High, a high-pressure system that brings warm, moist air from the tropics over the Japanese archipelago. July also marks the transition from the "Tsuyu" (rainy season) to the "mid-summer" peak. While the rainy season typically ends by mid-July in central Japan, the humidity remains, often making temperatures of 30°C (86°F) feel like 38°C (100°F). Geographically, the country is uniformly hot, though the northern island of Hokkaido remains a few degrees cooler and lacks a formal rainy season. This is the season of "Matsuri" (summer festivals) and fireworks, as the heat encourages outdoor celebrations after sunset. It is also the start of the official climbing season for Mount Fuji, as the snow has finally melted from the summit. Visitors in 2026 should be prepared for sudden "Guerrilla Rain" (short, intense downpours) and should carry a towel and handheld fan to manage the persistent, sticky humidity that defines the Japanese July.