The rest of this Friday afternoon could bring short, heavy downpours and thunderstorms to the Central Valley, the northern zone and the Caribbean. If you still have to get somewhere today, plan your trip around them. The National Meteorological Institute (IMN) expects intense storms lasting one to three hours, with 20 to 40 millimeters (0.8 to 1.6 inches) of rain in most affected areas. In the Central Valley, the Caribbean and the northern zone, totals could reach 70 millimeters (2.8 inches).
That much rain in a short window can overwhelm city drains and push creeks over their banks, especially in the Central Valley. If you live or park near a stream or on a street that floods, move your car early and don’t drive through standing water. Wind is the other risk. Isolated gusts could reach 80 kilometers per hour (50 mph), strong enough to bring down branches and power lines. When a storm hits, get indoors and keep away from trees and fallen cables.
The mountains and the eastern and northeastern parts of the Central Valley have the highest chance of storms. Rain could also spread to the northern lowlands and the northern Caribbean. On the Pacific side, expect storms in the mountains of the Central and South Pacific. The Nicoya Peninsula and the southeast of the North Pacific should see less activity.
The storms come in bursts rather than as an all-day rain. If one hits while you’re on the road or about to drive home, it is usually safer to wait it out than to push through it. The reason for the change is the trade winds. They usually keep the Pacific side dry at this time of year, and earlier this week they were bringing strong gusts across the country. Now they have weakened, which lets sea breezes and westerly winds carry moist Pacific air inland. Warm temperatures then build storm clouds over the mountains by afternoon.
This back-and-forth is typical of the transition from the rainy season to the dry season, which has already begun in Guanacaste and the Central Valley. Unsettled weather continues into Saturday, with more chances of afternoon rain. From Tuesday, the IMN expects rising pressure over the Caribbean Sea to strengthen the trade winds again.
If you’re driving between the Central Valley and the Caribbean coast, keep an eye on Route 32. Heavy rain in the mountains is what brings rock and mud down onto the highway through Braulio Carrillo National Park, which has closed repeatedly this year. If Route 32 closes, the usual alternatives are Route 10 through Turrialba and Route 126 through Vara Blanca. Both are narrower and slower, so leave extra time.
Check the IMN’s website and social media for updated warnings before you head out this afternoon or on Saturday.
