San José sits at 1,100 metres in the Central Valley, which means a spring-like temperature year-round — typically 18–24°C, cooling to 14–16°C at night. There is no oppressive heat and no cold to worry about, which is one of the city's most pleasant qualities. The main variable is rain.
The dry season runs from December through April. These are the most comfortable months for city visits: clear mornings, afternoon clouds, minimal rain, and easier access to the beaches and volcanoes for day trips. January and February are peak tourist months; March and April are somewhat quieter and still dry.
The rainy season (May through November) brings afternoon showers, usually heavy and brief, from about 2pm onward. Mornings are typically clear and the city continues to function normally. July and August have a brief dry spell (the veranillo) that makes them acceptable if prices and crowds are a consideration. September and October are the wettest months.
December brings a festive atmosphere — Christmas decorations go up early and the city becomes unusually animated with Fiestas Navideñas in the weeks before Christmas.