Planning for the weather is a good way to make your trip to Nozawaonsen relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July with an average temp of 74°F, while the coldest months are February and January with an average of 38°F. The rainiest months in Nozawaonsen are December, July, January, and September, with each month seeing an average of 10 inches of rainfall.