January is the driest month in Japan, making it an ideal time for tourists who want to explore outdoor activities such as skiing, snowboarding, or hiking without worrying about heavy rainfall. The low precipitation levels are due to the cold air from Siberia covering much of the country and the high-pressure system over the Pacific Ocean preventing the formation of low-pressure systems that typically bring in rain. Some regions experience high amounts of precipitation during this period, including Okinawa and the southern islands of Kyushu. Tourists should pack warm clothing such as jackets, gloves, hats, and boots when visiting Japan in January.