Q COSTA RICA — The national weather service, the Instituto Meteorológico Nacional (IMN), projects a rainfall deficit of up to 70% in July and nearly 60% between August and October in the North Pacific region of Costa Rica.
This reduction in precipitation is due to the intensification of the El Niño phenomenon, which, according to the agency, will maintain meteorological drought conditions for the rest of the year and could extend its effects until April 2027.
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In the Central Pacific, the South Pacific, and the Central Valley, the IMN estimates that the rainfall deficit will be around 50% in July and approximately 40% during the following quarter.
Conversely, the Caribbean and the eastern part of the Northern Zone are expected to experience normal or above-average rainfall.
Average temperatures will also be above normal. The North Pacific will experience the greatest increase, with values forecast to be between 1.5°C and 2.0°C above average. The Central Valley and the coasts of the South and Central Pacific will show increases of between 0.5°C and 1.5°C, while the Caribbean will see rises of 0.5°C to 1.0°C.
El Niño Intensifies and Changes Rainfall Patterns
According to the IMN, the influence of a strong El Niño will dominate the second half of 2026.
Karina Hernández, a specialist in the institution’s Climatology Unit, explained that the most recent revision of the forecasts not only increased the expected rainfall deficit but also reinforces the prediction that the phenomenon will reach a very strong intensity toward the end of the year. The IMN is observing clear signs of strengthening in the behavior of the ocean and the atmosphere.
The El Niño phenomenon involves an anomalous warming of the surface waters of the equatorial Pacific for several months, altering atmospheric circulation and precipitation patterns in many regions. In Costa Rica, this translates into less rainfall on the Pacific slope and in the Central Valley, while the Caribbean may experience normal or above-average rainfall.
“We are definitely seeing an intensification of El Niño. Everything points to a strong, and eventually very strong, El Niño toward the end of the year,” explained Hernández.
Extended Midsummer Dry Season and Anomalous Weather Patterns
The midsummer dry season, or canícula, began earlier than usual, at the end of June, and will extend throughout August. Hernández described this as unusual and warned that it will not only be longer but also more intense, increasing the number of consecutive days without rain, especially in the Pacific and Central Valley regions.
The IMN warns that the phenomenon not only affects the total monthly rainfall but can also cause very intense downpours in just a few days followed by several days with almost no precipitation. The reduced cloud cover facilitates the penetration of solar radiation and raises temperatures.
The peak intensity of El Niño is expected toward the end of 2026, with surface temperatures in the equatorial Pacific potentially exceeding 2.0 °C above average.
Hernández noted that although the phenomenon is expected to begin weakening in early 2027, the climatic impact could persist until April.
As background, the 2015 episode reached 2.8 °C, a range that the IMN considers possible for the end of 2026.