Weather is probably a major factor when you plan your trip to San Isidro, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually May and June, with an average temperature of 28°C, while the coldest months are February and January, with an average of 25°C. The rainiest months in San Isidro are December, September, July and October, with each month seeing an average of 384 mm of rainfall.