The National Meteorological Institute (IMN) has issued an alert for heavy rainfall and thunderstorms nationwide on Tuesday, as weather conditions are expected to intensify during the ongoing rainy season.

The 43rd tropical wave of the season (which typically runs from May through November) is forecast to bring strong showers and storms to much of the country throughout the day.

The stormy system was moving across Panama’s Caribbean Coast on Monday and is expected to generate widespread downpours and thunderstorms as it travels over Costa Rica.

Although the disturbance is forecasted to pass within 24 hours, the IMN cautioned that lingering moisture could cause additional showers through Wednesday.

Experts said the storm’s strength is being fueled by the Intertropical Convergence Zone, a belt of low pressure near the equator that often produces storm activity. The zone currently spans Costa Rica, extending from the Pacific Ocean to the Caribbean Sea.

Meteorologists expect the tropical wave season to end in November, marking the transition from the rainy season to the dry season, which typically begins in December.

Rainfall forecasts by region include:

• Central Mountain Range: 50 to 100 millimeters (2–6 inches), with the heaviest rain at higher elevations.

• Pacific Coast (Guanacaste, Puntarenas): 20 to 50 millimeters (1.5–3 inches).

• Central Valley (San José, Alajuela, Heredia, Cartago): 20 to 40 millimeters (0.8–1.5 inches).

• Caribbean Coast (Limón): 15 to 40 millimeters (0.6–1.5 inches).

The National Emergency Commission (CNE) has issued a Yellow Alert, the third-highest warning level, for the entire country. The alert urges local emergency response units to remain ready for potential large-scale weather impacts.

As of Monday, officials had not announced any additional Green, Yellow, or Red alerts related to the current weather pattern.

The Ministry of Public Works and Transportation (MOPT) has issued a precautionary notice for Route 32, the main highway between San José and Limón.

Officials warn that overnight closures are possible due to heavy rainfall and landslide risks. Drivers are urged to consider alternate routes, such as Route 10 through Turrialba Canton (Cartago) and on to Siquirres Canton  (Heredia), before rejoining Route 32 toward Limón. Traffic updates will be shared through MOPT’s official social media channels.

Authorities are advising residents to take the following precautions:

• Avoid rivers, lakes, and other bodies of water during heavy rain.

• In mountain areas, watch for landslides and falling debris.

• Households and businesses in flood-prone zones should review evacuation plans.

• Drivers should beware of flooding, slick roads, and low visibility.

• Stay indoors during thunderstorms and avoid electronic devices.

• Watch for strong winds that could bring down trees or power lines.

• Call 911 to report flooding, landslides, or fallen trees.

IMN is a government agency responsible for issuing weather forecasts, hazardous weather warnings, and related services to protect the public and inform organizations.

CNE works in partnership with communities and emergency responders to strengthen the nation’s preparedness, response, and recovery from natural hazards.

MOPT is the government agency responsible for managing the country’s roads, ports, and airports, as well as overseeing public transportation policy.

A.M. Costa Rica encourages readers to share this weather advisory with family, friends, and neighbors.