Temperatures are constant throughout the year in San Jose, ranging between the mid 70s and low 80s. Unlike other locations, Costa Rica is not defined by  the seasons you might be used to such as spring or fall. Instead, there is a rainy season and a dry season. The dry season runs from about mid-December through April, which, not-coincidentally coincides with the high season. During the rainy season (May to early December), the daily pattern is sun in the morning and rain showers in the early afternoon, after which the weather clears. On average, February is the driest month, while September receives the most rain.