Costa Rica will see a steady increase in rainfall through the final week of May, with Tropical Wave No. 5 expected to deliver the heaviest downpours of the week on Thursday, according to the National Meteorological Institute (IMN). The system, combined with the Intertropical Convergence Zone (ITCZ), is forecast to produce strong afternoon and evening showers and possible thunderstorms across much of the country, the IMN said in its weekly trend bulletin covering today, the 26th, through June 1.
The week began with light, scattered rain along the Caribbean coast during the morning hours and isolated afternoon showers in mountain areas, the Central Pacific and the South Pacific, the institute reported. The North Pacific and the Central Valley remain drier today with warm temperatures and partly cloudy skies.
Trade winds will continue early today, favoring overnight and morning rain in the Caribbean. Beginning Wednesday, those winds will weaken and humidity will rise, the IMN said, bringing more afternoon rain to the Pacific slope, the Northern Zone, the Caribbean mountains and parts of the Central Valley.
The peak of the week’s wet pattern will come on Thursday, when Tropical Wave No. 5 moves over our country alongside the ITCZ. Forecasters expect heavy downpours and possible electrical storms across most regions during the afternoon and evening hours. Rain associated with the system will continue into Thursday night and Friday night across the Pacific and the Central Valley, according to the bulletin.
By the weekend, afternoon rainfall will continue over the Pacific, the Northern Zone and mountain areas, but in a more localized pattern. Caribbean precipitation will turn more scattered, with the highest probability of rain shifting to the overnight and early-morning hours.
The IMN’s forecast lists expected maximum temperatures of 33 degrees Celsius (91°F) for the North Pacific, Central Pacific, South Pacific and Northern Zone, with overnight lows ranging from 13 to 18 degrees (55°F to 64°F) . The Central Valley will see highs near 29 degrees (84°F) and lows around 12 degrees (54°F), while the Caribbean is expected to reach 31 degrees (88°F) during the day with lows near 18 (64°F).
Those in the Central and South Pacific — including the beach destinations of Jacó, Manuel Antonio, Dominical and Uvita — will find the best windows for outdoor activity in the morning hours, with afternoon and evening thunderstorms increasingly likely from midweek onward. Guanacaste and the North Pacific will continue to have the driest conditions in our country, as the rainy-season pattern there is still getting started.
Those of you in the Caribbean, for example, Puerto Viejo, Cahuita and Tortuguero should plan for early-morning and overnight showers throughout the week. If you’re driving through the mountains, including the Cerro de la Muerte, Braulio Carrillo and the route to Monteverde, expect reduced visibility and slick road conditions during the heaviest storms on Thursday and Friday.
The National Emergency Commission (CNE) has urged the public to use caution on rural roads, near unstable slopes and along rivers, where runoff can rise rapidly during tropical-wave passages. Authorities also recommend clearing storm drains and securing loose outdoor items ahead of Thursday.
For those new to our country or just visiting, Costa Rica’s rainy season, which typically runs from May through November, has been arriving gradually this year. The IMN has warned that the broader 2026 outlook is shaped by an extended El Niño event, which is expected to bring drier-than-average conditions overall through 2027, even as individual tropical waves continue to deliver intense short-term rainfall.
Updates and official advisories are available at imn.ac.cr. or you can refer to our Costa Rica Weather Forecast.
