Guatemala has one of the most pleasant climates on earth – the tourist board refers to it as the “land of the eternal spring” – with much of the country enjoying warm days and mild evenings year-round (see Average monthly temperatures and rainfall). The climate is largely determined by altitude. In those areas between 1300 and 1600m, which includes Guatemala City, Antigua, Lago de Atitlán and Cobán, the air is almost always fresh and the nights mild and, despite the heat of the midday sun, humidity is never a problem. Parts of the departments of Quetzaltenango, Huehuetenango and El Quiché are above this height, and so have a cooler, damper climate with distinctly chilly nights between early December and late February. Low-lying Petén suffers from sticky, steamy conditions most of the year, as do the Pacific and Caribbean coasts, though here at least you can usually rely on the welcome relief of a sea breeze.
The rainy season runs roughly from May to October, with the worst of the rain falling in September and October. In Petén, however, the season can extend into December. Even at the height of the wet season, though, the rain is usually confined to late afternoon downpours with most of the rest of the day being warm and pleasant. Visiting Petén’s more remote ruins is best attempted between February and May, as the mud can be thigh-deep during the height of the rains.
The busiest times for tourism are between December and March, and again in July and August. Language schools and hotels are fullest during these periods, and many of them hike their prices correspondingly.