Weather is probably a major factor when you plan your trip to Toyotomi Onsen, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July, with an average temperature of 17°C, while the coldest months are February and January, with an average of -3°C. The snowiest months in Toyotomi Onsen are January, February, March and December, with each month seeing an average of 77 cm of snowfall.