If you're hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Tzununa: The hottest months are usually March and April with an average temp of 61°F, while the coldest months are January and December with an average of 60°F. The rainiest months in Tzununa are June, September, May, and August, with each month seeing an average of 19 inches of rainfall.