Costa Rica has settled into textbook rainy season conditions as we close out September and welcome October. The Intertropical Convergence Zone has repositioned itself near our territory and shows no signs of backing down, bringing the high humidity and atmospheric instability that defines this time of year.
This week we’ll see the classic tropical rhythm many Costa Ricans and residents know by heart: warm, pleasant mornings that gradually build into cloud-heavy afternoons and rumbling thunderstorms. But unlike some weeks where afternoon rains wrap up by evening, expect precipitation and storms to linger well into nighttime hours across multiple regions.
Weekend Alert: Costa Rica’s Meteorological Institute is calling for a significant uptick in rainfall coverage and intensity as the week progresses. Saturday and Sunday are shaping up to be particularly wet across the national territory, so plan indoor activities and prepare homes/properties for heavy downpours.
Tropical Wave Status: Luckily no tropical waves are in the forecast this week, so we don’t have to worry about adding more complexity to the already anticipated rain events.
The AM hours this week will typically begin with partly cloudy skies creating pleasant conditions across most of the country. It’s the golden hour for outdoor activities but scattered morning rainfall remains a possibility, especially near coastal areas. The temperature gradient between overnight lows and morning warmth may create fog banks in mountainous regions and the Central Valley, particularly during the first half of the week. Drivers in elevated areas should use caution during early morning commutes.
The Pacific slope, Central Valley, and Northern Zone transition from partly cloudy to mostly cloudy skies as atmospheric energy builds throughout the day. Showers and thunderstorms can develop in the early-to-late afternoons throughout the week.
The Caribbean region on the other hand will have partly cloudy conditions that spawn rain and scattered thunderstorms, particularly in mountainous areas where orographic lift amplifies storm development. Coastal Caribbean areas may see less intensive rainfall than their mountain counterparts.
Unlike past weeks where storms have dissipated at sunset, this week we could see persistent nighttime precipitation:
Pacific Region: Expect mostly cloudy skies with active rain and thunderstorm systems, especially along coastal areas during early evening hours. These coastal storms can be quite dramatic, with lightning shows visible from beach communities.
Central Valley: Mostly cloudy conditions prevail with rainfall during early nighttime hours. Fog banks return as temperatures drop, particularly early in the week.
Northern Zone: Partly to mostly cloudy skies maintain rain and thunderstorm potential throughout the evening hours, keeping conditions unsettled well after dark.
Caribbean: Partly cloudy conditions with light mountain rain possibilities. Fog banks may develop in elevated areas.
Best Weather Windows: Early to mid-morning hours throughout the week offer the most reliable dry conditions for activities requiring clear skies.
Weekend Preparations: With enhanced rainfall predicted Saturday and Sunday, stock up on what you might need and plan indoor activities.
Fog Advisory: Mountain drivers and Central Valley commuters should allow extra travel time during early morning hours, particularly Monday through Wednesday.
Temperature patterns reflect active rainy season conditions with moderate highs due to persistent cloud cover and comfortable lows influenced by elevated humidity levels:
| Region | High °C (°F) | Low °C (°F) |
|---|---|---|
| Central Valley | 31° (87.8°) | 15° (59°) |
| North Pacific | 34° (93.2°) | 20° (68°) |
| Central Pacific | 33° (91.4°) | 15° (59°) |
| South Pacific | 33° (91.4°) | 15° (59°) |
| Caribbean | 32° (89.6°) | 20° (68°) |
| Northern Zone | 34° (93.2°) | 17° (62.6°) |
This forecast is based on the weekly outlook from Costa Rica’s National Meteorological Institute (IMN) and other meteorological sources.
