Weather is probably a major factor when you plan your trip to El Arenal, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually March and February, with an average temperature of 25°C, while the coldest months are August and September, with an average of 22°C. The rainiest months in El Arenal are March, February, April and January, with each month seeing an average of 259 mm of rainfall.