Published on Wednesday, July 9, 2025
By the A.M. Costa Rica staff

A massive cloud of Saharan dust, known as Saharan Air Layer (SAL), is currently crossing Costa Rica after drifting westward across the Atlantic Ocean, according to the Weather Institute (IMN).

The thick dust plume, which originated off the coast of West Africa, has already traveled more than 3,000 miles across the Atlantic and into the Caribbean. It is now moving through the country and will continue to affect conditions throughout the week.

Meteorologists say the arrival of the dust is contributing to drier weather, reduced air quality, and higher-than-normal temperatures in many parts of Costa Rica.

“These fine particles can trap heat near the surface,” experts explained, “which is expected to push temperatures above average, especially in coastal and urban areas.”

Health officials warn that inhaling the dust can irritate the respiratory system and worsen allergies, asthma, and other respiratory conditions.

According to the IMN, the dust is expected to begin dispersing over the weekend.

This weather phenomenon coincides with a stretch of sunny July weather in Costa Rica, a period commonly known in North America as the "Dog Days of Summer."

The Dog Days, typically the hottest and most humid part of the year in the Northern Hemisphere, also affect Central America. In North America, this period typically begins in July and lasts between 30 and 60 days.

In Costa Rica, the IMN forecasts that this mid-year pattern will bring sunnier skies, lower humidity, and stronger easterly winds across the Pacific coast and Central Valley throughout most of July.

The National Meteorological Institute (IMN), known as the Weather Institute, is a government agency responsible for issuing weather forecasts, hazardous weather warnings, and related services to protect the public and inform organizations.

----------------
What have you heard about the effects of the Saharan dust in your country?  We would like to know your thoughts on this story. Send your comments to news@amcostarica.com