Weather is probably a major factor when you plan your trip to Costa Rica, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and October, with an average temperature of 28°C, while the coldest months are July and June, with an average of 24°C. The rainiest months in Costa Rica are January, December, February and March, with each month seeing an average of 242 mm of rainfall.