Last updated: August 23, 2025
In December, the average temperature in San Isidro, Costa Rica hovers around 22°C (72°F), with a comfortable minimum of 18°C (65°F) and a pleasant maximum of 25°C (77°F). Be prepared for a rainy experience, as the region sees about 354 mm (13.9 in) of precipitation spread over 29 days, contributing to an average humidity of 72%.
In December in San Isidro, the average temperature is 22°C (72°F). Maximums can reach 25°C (77°F), and minimums can be as low as 18°C (65°F). This climate makes it an ideal time for outdoor adventures and exploring the local attractions.
In San Isidro in December, the precipitation amount is 354 mm (13.9 in) spread over a duration of 29 days.
In San Isidro in December humidity is 72%. With an average temperature of 22°C (72°F), this humidity feels like you are stepping into a warm, embracing blanket, making traveling feel sweaty and slightly stifling, but the balmy weather is also quite perfect for exploring local attractions.
In San Isidro in December, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in San Isidro.
UV Risk Categories
Weather in San Isidro varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in San Isidro, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 22°C (72°F) | 194 mm (7.6 inches) | 68% | extreme |
| February Weather | 22°C (73°F) | 99 mm (3.9 inches) | 68% | extreme |
| March Weather | 23°C (73°F) | 120 mm (4.7 inches) | 66% | extreme |
| April Weather | 23°C (73°F) | 350 mm (13.8 inches) | 67% | extreme |
| May Weather | 23°C (73°F) | 742 mm (29.2 inches) | 69% | extreme |
| June Weather | 23°C (73°F) | 663 mm (26.1 inches) | 84% | extreme |
| July Weather | 22°C (73°F) | 784 mm (30.8 inches) | 85% | extreme |
| August Weather | 22°C (73°F) | 838 mm (33.0 inches) | 82% | extreme |
| September Weather | 22°C (72°F) | 766 mm (30.1 inches) | 81% | extreme |
| October Weather | 22°C (72°F) | 937 mm (36.9 inches) | 80% | extreme |
| November Weather | 22°C (72°F) | 885 mm (34.8 inches) | 80% | extreme |
| December Weather | 22°C (72°F) | 354 mm (13.9 inches) | 72% | extreme |