Q COSTA RICA — This year’s rainy season in Costa Rica has been anything but typical. Known for its predictable wet months from May through November, the country is experiencing a series of strange weather events that have caught residents and meteorologists off guard.
Usually, the rainy season brings steady downpours mainly in the afternoons and evenings, providing relief from the tropical heat. But this year, the pattern has shifted. Instead of gradual rains, many areas in Costa Rica have seen sudden, intense storms that hit without warning, often followed by long stretches, days at times, of unexpected dryness. And intense heat.
But today, Tuesday, Tropical Wave No. 41 is expected to enter Costa Rica, while the country is still recovering from the effects of the previous wave, which 48 hours earlier caused flooding in five cantons and power outages in parts of Puerto Jiménez.
Tropical Wave No. 40, which crossed the country on Sunday, brought up to 80 millimeters of rain to the Osa Peninsula, 50 mm to the Limón airport and Laurel, and 40 mm to Pérez Zeledón, according to the national weather service, the Instituto Meteorológico Nacional (IMN).
These rainfall totals saturated soils already affected by weeks of continuous precipitation.
CNE has issued a green alert for four regions of the country
The Comisión Nacional de Emergencias (CNE)—National Emergency Commission—maintains a green alert for rains in the Caribbean slope, the Northern Zone, the Central Pacific, and the South Pacific.
The measure responds to both the impact of the recent tropical wave and the approaching weather system.
The CNE reported incidents on Sunday in Osa, Golfito, Puerto Jiménez, Pérez Zeledón, and Limón.
“In several sectors of Puerto Jiménez, weather conditions caused a temporary power outage. The agencies working in the area managed to restore service,” the CNE stated.
Storms from Tropical Wave No. 41 are expected to start forming early this Tuesday morning off the coast of Limón. Starting Wednesday, they will become more prevalent in the Caribbean and the Northern Zone. In the Pacific, rainfall will be isolated and concentrated in the afternoons.
For the Central Valley, the IMN anticipates occasional rains moving in from the mountains, with less intensity than those expected in the coastal regions.
An El Niño phenomenon complicates the medium-term forecast
The underlying climate context adds a paradox to the outlook: despite the succession of tropical waves, the IMN projected a rainfall deficit in the Pacific, the Central Valley, and the Northwest Zone for the remainder of September and the first days of October.
“This deficit is due to the continued presence of an established El Niño phenomenon, along with atmospheric conditions that generate stronger-than-normal trade winds, a highly atypical behavior for September that will decrease rainfall activity on the Pacific slope,” the institute stated, according to El Observador.
The Caribbean and the Northern Zone, on the other hand, are expected to experience rainfall during the first two weeks of the month.
Since the onset of El Niño this season, many regions in Costa Rica have experienced noticeably reduced rainfall. The Pacific side, typically drier than the Caribbean coast, has felt the brunt of the dryness, with some areas reporting the driest conditions in years. This dry spell is not just a minor inconvenience. It threatens agriculture, from coffee plantations to staple crops, which rely heavily on predictable rainy periods.
Tropical Wave No. 42 is now on the IMN’s radar
The IMN says it is monitoring Tropical Wave No. 42, which is expected to approach Costa Rica early next week. At the moment, the system is not showing significant development, although authorities are continuing to monitor it.
The Intertropical Convergence Zone also remains active over the Pacific waters near the country. This condition, combined with the unstable atmospheric pattern that emerged over the weekend, supports a scenario of rain that will extend at least until Wednesday, with greater intensity in the Atlantic regions.
The IMN also forecasts a gradual increase in wind speed over the north of the national territory today, which could intensify the conditions prior to the arrival of the new wave.