Q COSTARICA — The national weather service, Instituto Meteorológico Nacional (IMN), predicts that the end of the rainy season in Costa Rica will be later in 2025.
According to experts, the rainfall pattern will extend beyond usual end of October due to factors such as:
- A Pacific Ocean in a cold neutral phase
- A warmer-than-normal Caribbean Sea
- A delayed start to the cold snap season
“It is quite likely that the end of the rainy season will be delayed,” Karina Hernández of the IMN Climatology Unit confirmed.
Factors Sustaining the Rainfall
In addition to the aforementioned factors, the Intertropical Convergence Zone (ITCZ) will remain active over the country, ensuring frequent rainfall throughout the season.
Although it may not be felt with the same intensity on some days, its presence is decisive.
Another key element is the cold snaps, which usually begin in November, marking the beginning of the dry season.
According to Hernández, this year, as in 2024, we will have a delayed transition.
“Cold bursts are very important, especially for the Caribbean. The 2025-2026 season will start late, and that contributes to the rains lasting longer,” the specialist explained.
The IMN will not provide the expected dates for the end of the rainy season by region until mid-October.
A wetter October
According to forecasts, October will have rainier-than-normal conditions in the Pacific, the Central Valley, and the Northwest, with up to a 15% surplus.
In contrast, the Caribbean will face a deficit of close to 10%, accompanied by slightly warmer temperatures, up to half a degree above average.
“October is already one of the rainiest months of the year, but now it is expected to be more sustained. A 15% surplus is already quite significant,” Hernández explained.
The IMN highlights that September showed irregular rainfall, with dry days and others that were more intense, but October will be more consistent.
Furthermore, tropical waves will continue to bring moisture, although not all of them will develop into cyclones.
“October is still part of the peak of the hurricane season, which increases the possibility of tropical waves or even storms affecting the country,” he added.
According to the weekly forecast, the following is expected:
- September 29 to October 5: The entire Pacific region will experience more than normal rainfall, with weekly amounts of 90 to 120 mm. The Caribbean region will experience less rain, and the rest of the country will experience normal rainfall.
- October 5 to 12: The Pacific region will experience normal seasonal rainfall. The Caribbean region will maintain a less rainy pattern.
- October 13 to 19: The Pacific region and Central Valley will experience above-average rainfall. The Caribbean region will return to a normal pattern with little precipitation.
- October 20 to 26: The Pacific region and Central Valley will experience more than normal rainfall. The Caribbean region will again experience less rain.
- October 27 to November 2: This week, the entire Pacific region will continue to experience normal seasonal rainfall. The Caribbean region is expected to return to a seasonal rainfall pattern, while the rest of the country will experience normal rainfall.
- Temperatures are expected to be within normal range.
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