This week showcases the classic transition between Costa Rica’s dry and rainy seasons, with conditions shifting noticeably as we move through the coming days. Monday brought isolated afternoon showers, mainly affecting the Pacific, Central Valley, and mountain ranges.
The next couple of days bring a partial reduction in humidity along with moderate trade winds in the Caribbean Sea basin, favoring less cloud development across the country, though isolated showers and downpours in the Central and South Pacific remain possible.
Starting Thursday, humidity gradually increases nationwide, promoting cloud development and a more widespread pattern of rain and downpours across various areas, especially on the Pacific slope and in the mountains of the Caribbean and Northern Zone. The probability of thunderstorms increases significantly between Friday and Sunday.
Warm conditions persist throughout the week with the muggy feeling characteristic of late April and early May as moisture builds in the atmosphere.
Monday saw transitional conditions with isolated afternoon showers and thunderstorms, mainly in the Pacific and mountain regions, with early evening shower activity in Pacific and mountainous areas.
Mid-week brings a temporary reduction in moisture and clearer skies as trade winds temporarily limit cloud development. This is happening now through Wednesday.
Mornings: Clearer conditions prevail across the country. Partly cloudy with reduced cloud cover.
Afternoons: Isolated showers and thunderstorms remain possible, mainly in the Central and South Pacific and mountain regions, though less widespread than Monday.
Evenings: Variable conditions with partly to occasionally cloudy skies. Limited shower activity.
The weekend brings a significant increase in atmospheric moisture, offering a preview of the coming rainy season pattern.
Mornings: Increased cloud cover develops, especially in the Caribbean and Northern Zone. Partly cloudy conditions across most areas.
Afternoons: More widespread showers and thunderstorms develop, particularly on the Pacific slope and in Caribbean and Northern Zone mountains. Friday through Sunday see the week’s most active rainfall.
Evenings: Partly to occasionally cloudy skies with showers likely in the Pacific and mountainous areas during early evening hours, especially over the weekend.
Pacific Slope: Monday saw isolated afternoon showers, with brief relief coming Tuesday and Wednesday. Thursday onward brings more widespread afternoon showers and thunderstorms as moisture increases. Weekend sees the most active conditions.
Central Valley: Monday saw isolated afternoon showers. Drier Tuesday and Wednesday. Increasing shower and thunderstorm potential Thursday through the weekend as humidity builds.
North Pacific/Guanacaste: Very hot with highs reaching 38°C (100.4°F). Isolated shower potential throughout the week, though generally the driest region. Muggy conditions develop as humidity increases despite minimal rainfall.
South Pacific: Most active Pacific region for rainfall. Isolated downpours possible even during Tuesday and Wednesday’s drier period. Widespread activity Thursday through Sunday.
Caribbean & Northern Zone: Mountain areas see increased cloud cover building toward the weekend. Friday through Sunday bring more widespread rainfall to mountainous regions and surrounding areas.
This week perfectly demonstrates Costa Rica’s dry-to-rainy season transition. The pattern isn’t a simple switch but rather a gradual increase in atmospheric moisture and rainfall frequency.
Warm temperatures persist with increasing mugginess as humidity builds:
| Region | High °C (°F) | Low °C (°F) |
|---|---|---|
| Central Valley | 32° (89.6°) | 12° (53.6°) |
| North Pacific | 38° (100.4°) | 20° (68°) |
| Central Pacific | 33° (91.4°) | 12° (53.6°) |
| South Pacific | 35° (95°) | 12° (53.6°) |
| Caribbean | 32° (89.6°) | 15° (59°) |
| Northern Zone | 33° (91.4°) | 18° (64.4°) |
The North Pacific’s 38°C (100.4°) represents extreme heat in Guanacaste, made worse by increasing humidity creating muggy conditions. The South Pacific’s 35°C (95°F) combined with higher moisture levels will feel particularly oppressive. Despite warm to hot days, overnight temperatures remain surprisingly cool in some regions, with the Central Valley, Central Pacific, and South Pacific all dropping to 12°C (53.6°F).
The increasing humidity makes temperatures feel warmer than the actual readings, especially during afternoons when moisture peaks. This muggy feeling is characteristic of the transitional period and will intensify as the rainy season fully establishes in the coming weeks.
While officially still in the transition period, this week marks the beginning of Costa Rica’s shift toward rainy season patterns. The increasing humidity, afternoon cloud buildup, and weekend thunderstorm activity signal the approaching wet months.
This forecast is based on outlooks from Costa Rica’s National Meteorological Institute (IMN).
