If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Jalcomulco: The hottest months are usually April and May with an average temp of 67°F, while the coldest months are January and February with an average of 59°F. The rainiest months in Jalcomulco are September, June, August, and May, with each month seeing an average of 11 inches of rainfall.