A massive cloud of Saharan dust, known as the Saharan Air Layer (SAL), is expected to move over Costa Rica during the next five days, bringing drier conditions, abundant sunshine and above-average temperatures, according to the National Meteorological Institute (IMN).

The dense dust plume originated off the coast of West Africa and has traveled more than 3,000 miles across the Atlantic Ocean into the Caribbean. It is now moving through the Caribbean Sea and is forecast to reach Costa Rica beginning Wednesday.

Meteorologists said the arrival of the Saharan dust will create drier weather and contribute to higher-than-normal temperatures across much of the country.

"These fine particles can trap heat near the surface," meteorologists said. "Noting that temperatures are expected to rise above seasonal averages, particularly in coastal and urban areas."


The North Pacific region, including Guanacaste Province, is expected to experience mostly sunny skies, with temperatures ranging from 86 to 102°F.

In the Central Valley, which includes the provinces of San José, Alajuela, Heredia and Cartago, as well as the Central Pacific region in Puntarenas Province, temperatures are forecast to range from 77 to 86 °F.

Along the Caribbean Coast in Limón Province, temperatures could reach 86 °F.

The Ministry of Health warned that inhaling the dust may irritate the respiratory system and worsen allergies, asthma and other respiratory conditions.

According to the IMN, the dust plume is expected to begin dispersing by Friday.

The National Emergency Commission (CNE) recently issued an alert for parts of the Pacific Coast because of an anticipated reduction in rainfall.

However, meteorologists cautioned that tropical waves moving through the region could still produce brief periods of heavy rain in many parts of the country despite the presence of the Saharan dust.

Costa Rica has a tropical and subtropical climate with two primary seasons. The dry season, commonly known as summer, typically runs from December through May. The rainy season extends from June through November and generally coincides with the Atlantic hurricane season.

The IMN is the government agency responsible for issuing weather forecasts, hazardous weather alerts and related services designed to protect the public while providing weather information to government agencies, businesses and residents.

The CNE is the government agency responsible for coordinating with communities and emergency responders to strengthen the nation's preparedness, response and recovery efforts related to natural hazards.

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