If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in San Andrés Tuxtla: The hottest months are usually May and April with an average temp of 80°F, while the coldest months are January and February with an average of 70°F. The rainiest months in San Andrés Tuxtla are October, September, November, and August, with each month seeing an average of 14 inches of rainfall.