The country’s climate is classified as tropical and subtropical, with two primary seasons. The dry season, often referred to as summer, typically runs from December through May, while the rainy season extends from June through November, closely aligning with the Atlantic hurricane season.

Despite the seasonal shift, a brief period of drier weather is expected during the rainy months. This phenomenon, known as the "Veranillo de San Juan," usually occurs near the end of June. Named after the June 24 Christian feast day celebrating the nativity of John the Baptist. The event typically brings about a week of sunnier conditions across much of the country and coincides with the “Dog Days of Summer” period in North America.

Costa Rica’s tropical climate remains relatively stable year-round due to its location approximately 12 degrees north of the Equator. However, rainfall patterns during the green season are heavily influenced by the Intertropical Convergence Zone (ITCZ), a band of clouds and thunderstorms that circles the globe near the Equator.

Later in the year, weather conditions are expected to be affected by the El Niño–Southern Oscillation (ENSO), a global climate pattern driven by changes in winds and sea surface temperatures in the tropical Pacific Ocean. The phenomenon is forecast to result in a rainfall deficit of 10% to 30% between September and November.

Meteorologists say the onset of rainfall will vary by region:

• Southern Pacific Coast (southern Puntarenas): Between April 27 and May 2.

• Central Valley (including San José, Cartago, and southern Heredia and Alajuela): Between April 29 and May 2.

• Central Pacific Coast (central and northern Puntarenas): Between May 2 and May 10.

• North Pacific Coast (Guanacaste): Between May 6 and May 13.

• Northern Zone (northern Heredia and Alajuela): Between May 11 and May 13.

• Caribbean Coast (Limón): Between May 13 and May 15.

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