In Tokyo, January is historically and statistically the driest month of the year. During this mid-winter period, the city frequently experiences clear, crisp blue skies with very little precipitation, often averaging only around 50mm of rainfall. This dry weather is caused by cold, high-pressure systems moving in from the Asian continent, which lose their moisture over the Japanese Alps before reaching the Pacific coast where Tokyo is situated. While the lack of rain makes it an excellent time for unobstructed views of Mount Fuji, the humidity levels drop significantly—sometimes as low as 20%—leading many residents to use humidifiers to combat the dry indoor air. Following January, December and February are also notably dry, contrasting sharply with the "Tsuyu" rainy season in June and the typhoon-heavy month of September, when the city can receive more than 200mm of rain.