Weather is probably a major factor when you plan your trip to Antigua Guatemala, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually April and March, with an average temperature of 20°C, while the coldest months are January and December, with an average of 18°C. The rainiest months in Antigua Guatemala are September, June, May and August, with each month seeing an average of 407 mm of rainfall.