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San Marcos Weather by Month
Average temperatures, rainfall and humidity for San Marcos, Costa Rica, month by month, built from OpenWeather’s historical records. Use it to see what a typical San Marcos month looks like before you travel — then check the live San Marcos forecast for the days ahead.
Warmest month
April
27°C average high
Coolest month
February
18°C average low
Wettest month
December
249 mm of rain
Driest month
March
80 mm of rain
Average temperature and rainfall in San Marcos by month
Averages of the daily highs and lows recorded in each month, with total rainfall, mean humidity and mean wind speed.
| Month | Avg high | Avg low | Record low / high | Rainfall | Humidity | Wind |
|---|---|---|---|---|---|---|
| January | 25°C | 18°C | 11°C / 32°C | 173 mm | 74% | 17 km/h |
| February | 26°C | 18°C | 10°C / 31°C | 123 mm | 71% | 19 km/h |
| March | 27°C | 18°C | 13°C / 31°C | 80 mm | 70% | 18 km/h |
| April | 27°C | 19°C | 13°C / 39°C | 156 mm | 75% | 14 km/h |
| May | 26°C | 19°C | 16°C / 38°C | 195 mm | 82% | 11 km/h |
| June | 26°C | 19°C | 10°C / 30°C | 168 mm | 86% | 9 km/h |
| July | 25°C | 19°C | 15°C / 32°C | 175 mm | 83% | 11 km/h |
| August | 26°C | 19°C | 10°C / 32°C | 127 mm | 83% | 10 km/h |
| September | 26°C | 19°C | 16°C / 31°C | 147 mm | 86% | 8 km/h |
| October | 25°C | 19°C | 15°C / 30°C | 164 mm | 87% | 7 km/h |
| November | 25°C | 18°C | 12°C / 30°C | 230 mm | 84% | 10 km/h |
| December | 25°C | 18°C | 13°C / 30°C | 249 mm | 77% | 15 km/h |
Best time to visit San Marcos
The most comfortable time to visit San Marcos is generally February to March and August, balancing mild daytime temperatures against the driest stretch of the year. Temperatures stay fairly even all year and rain concentrates around December, totalling about 1,986 mm a year.
Travellers who prefer heat should aim for April, when highs average 27°C. December is the month to avoid if rain would spoil your plans — it averages 249 mm, roughly 3× the rainfall of the driest month (March).
Source: OpenWeather historical and statistical weather data. Values are long-term averages, not a forecast — see the San Marcos forecast for what is happening now.