If you're hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Las Peñitas: The hottest months are usually March and April with an average temp of 83°F, while the coldest months are December and January with an average of 81°F. The rainiest months in Las Peñitas are October, September, June, and May, with each month seeing an average of 16 inches of rainfall.