Tokyo's 34-day rain streak ends; weather shifts to sun in October

Central Tokyo has recorded 34 consecutive days of rainfall through September 29, setting the longest continuous precipitation streak on record since measurements began in 1886. The previous record of 33 days was set from June 27 to July 29, 2019. The prolonged wet spell began on August 27 and was driven by multiple meteorological factors: typhoons (including Typhoon Dujuan on September 21, which dumped 156 mm), a stalled autumn rain front, and a trough of low pressure. A phenomenon known as an "atmospheric river"—a concentrated band of water vapor flowing from the Indian Ocean—also contributed to the sustained rainfall.

The impact has been substantial. September precipitation through the 28th reached 629 millimeters in central Tokyo, approximately three times the typical monthly average and approaching the 1958 September record of 670.9 mm. Sunlight hours for the month through September 27 totaled only 45.8 hours, tracking toward the second-lowest September on record. The Kanto region, which includes Tokyo and neighboring Chiba and Kanagawa prefectures, experienced severe flooding and landslides; Typhoon Dujuan alone caused 14 deaths in areas near the capital.

Japan's Meteorological Agency officials attributed part of the extended rainfall pattern to El Niño warming Pacific waters and a longer-than-usual residence time of the Pacific high-pressure system. While officials stated they cannot directly attribute the streak to climate change, a 2024 agency report noted that "global warming is having long-term effects on Japan's weather, including increased precipitation." Forecasters point to weakened tropical trade winds and the occurrence of an atmospheric river phenomenon as additional contributing factors.

Weather is expected to improve significantly by early October. Rain is predicted through October 1, with Typhoon Surigae potentially approaching the Kanto region. However, clearing is forecast from October 2 onward, with sunny days increasing and daytime temperatures rising to 25–26°C in Tokyo. The consecutive rainfall record will end once the rain stops, likely within days.