Getting an idea of what to expect from the weather in Ajigasawa will help you enjoy your stay to the fullest. The hottest months are usually August and July, with an average temperature of 21°C, while the coldest months are February and January, with an average of 2°C. The rainiest months in Ajigasawa are August, December, July and September, with each month seeing an average of 212 mm of rainfall.