Taking into account the local weather in San Isidro is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually May and June with an average temp of 82°F, while the coldest months are February and January with an average of 79°F. The rainiest months in San Isidro are December, January, July, and June, with each month seeing an average of 14 inches of rainfall.