Costa Rica is heading into a rainy season that may begin on schedule on the calendar, but not in the usual pattern. The Instituto Meteorológico Nacional (IMN) projects an irregular start to the season, followed by rainfall totals that could end up 10% to 30% below normal across much of the country for the rest of the year. The biggest shortfalls are expected later in the year, especially from September through November.
The rainy season is expected to arrive gradually, not all at once. Southern and central parts of the country will likely see the shift first, with northern areas following later. The Caribbean is different, since it does not have the same clearly defined dry and rainy seasons as the rest of Costa Rica.
The forecast also points to a hotter-than-usual year. IMN says temperatures are expected to run about 1 to 3 degrees Fahrenheit above normal, especially in the North Pacific. Even as the rainy season begins, many parts of Costa Rica are still likely to feel unusually warm and dry.
The drier pattern is tied to the likely return of El Niño during the second half of the year. Costa Rican forecasters say the odds of El Niño developing from mid-2026 onward are around 60%, and NOAA’s ENSO discussion similarly said neutral conditions are favored in the near term, with El Niño likely to emerge in May to July and persist through at least the end of 2026. For us here in Costa Rica, that usually means less rain and more heat across much of the country, especially on the Pacific side.
There is also a hurricane-season twist in the forecast. IMN expects the 2026 Atlantic season to be less active than normal, with 9 to 12 named systems compared with a climatological average of 14. That could reduce one of the outside sources of rainfall that sometimes helps Costa Rica during the wetter months. Even so, a quieter Atlantic does not remove the risk entirely. IMN has warned that at least one system could still affect the country indirectly.
Let’s end with today’s weather as the pattern fits that uneven transition. IMN’s daily forecast points to generally limited morning cloud cover, a moderate chance of late-day rain in the north and west of the Central Valley, showers in parts of the Central and South Pacific, and isolated rain in mountainous sections of the Caribbean. The final takeaway is that Costa Rica’s rainy season is starting, but in a patchy way, and 2026 is shaping up to be hotter and drier than a typical year
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