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Monthly climate in San Marcos, Costa Rica

Last updated: July 31, 2025

Under the Köppen–Geiger climate classification San Marcos features a tropical monsoon climate (Am). Temperatures typically range between 17 °C (63 °F) and 18 °C (66 °F) through the year, but rarely can drop to 11 °C (51 °F) or can rise to as high as 26 °C (79 °F). The average annual precipitation amounts to about 3345 mm (131.7 inches) and receives 253 rainy days on the 1 mm (0.04 inches) threshold annually. San Marcos enjoys an average of 3032 hours of sunshine throughout the year, and daylight varies from 11 hours 33 minutes to 12 hours 40 minutes per day.

Monthly average temperatures in San Marcos, Costa Rica

The warmest months in San Marcos are April, May and June, with daily mean temperatures ranging from 18 to 18 °C (65 - 66 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 17 to 18 °C (63 - 64 °F) throughout the day. On average each year, San Marcos experiences 0 days above 25 °C (77.0 °F) and 0 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in San Marcos. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Maximum24°C
(76°F)		25°C
(76°F)		25°C
(77°F)		26°C
(78°F)		26°C
(79°F)		25°C
(76°F)		24°C
(76°F)		25°C
(78°F)		25°C
(77°F)		24°C
(76°F)		24°C
(75°F)		24°C
(75°F)
Mean maximum23°C
(74°F)		24°C
(75°F)		24°C
(76°F)		24°C
(76°F)		24°C
(76°F)		24°C
(75°F)		24°C
(75°F)		24°C
(76°F)		24°C
(75°F)		24°C
(75°F)		23°C
(74°F)		23°C
(74°F)
Average high22°C
(71°F)		22°C
(72°F)		23°C
(73°F)		23°C
(73°F)		22°C
(72°F)		22°C
(73°F)		22°C
(72°F)		22°C
(72°F)		22°C
(72°F)		22°C
(71°F)		21°C
(71°F)		21°C
(71°F)
Daily mean17°C
(63°F)		18°C
(64°F)		18°C
(65°F)		18°C
(65°F)		18°C
(65°F)		18°C
(66°F)		18°C
(65°F)		18°C
(65°F)		18°C
(65°F)		18°C
(64°F)		18°C
(64°F)		17°C
(64°F)
Average low14°C
(57°F)		14°C
(57°F)		14°C
(58°F)		15°C
(60°F)		16°C
(61°F)		16°C
(61°F)		16°C
(60°F)		15°C
(60°F)		15°C
(60°F)		15°C
(60°F)		15°C
(59°F)		14°C
(58°F)
Mean minimum12°C
(54°F)		12°C
(54°F)		12°C
(55°F)		13°C
(56°F)		15°C
(58°F)		15°C
(59°F)		14°C
(58°F)		14°C
(58°F)		14°C
(57°F)		14°C
(57°F)		14°C
(57°F)		13°C
(55°F)
Minimum11°C
(51°F)		11°C
(51°F)		11°C
(53°F)		13°C
(55°F)		14°C
(57°F)		14°C
(57°F)		14°C
(57°F)		14°C
(57°F)		14°C
(57°F)		13°C
(55°F)		13°C
(56°F)		12°C
(54°F)

Compare climate in San Marcos with other places

Compare temperature, precipitation, sunshine, UV index in San Marcos, Costa Rica with other places around the world.

Monthly average precipitation in San Marcos, Costa Rica

San Marcos usually has the most precipitation in May, September and October, with an average of 29 rainy days and 547 mm (21.5 inches) of precipitation per month. The driest months in San Marcos are January, February and March. On average, 27 mm (1.1 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in San Marcos. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Average precipitation mm (inches)35 (1.4)19 (0.8)28 (1.1)155 (6.1)532 (21.0)399 (15.7)315 (12.4)403 (15.9)508 (20.0)601 (23.7)272 (10.7)78 (3.1)
Average precipitation days (≥ 1 mm)656232929283030302611

Monthly sunshine hours in San Marcos, Costa Rica

The sunniest months in San Marcos are February, March and December, when the sun shines an average of 10 hours 11 minutes a day. Least sunny months in San Marcos: August, September and October receive an average of 7 hours 1 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in San Marcos. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Mean monthly sunshine hours253297330294222225222222218205239299
Mean daily daylight hours11h 36m11h 48m12h 3m12h 20m12h 33m12h 40m12h 36m12h 24m12h 9m11h 53m11h 39m11h 33m

Solar UV radiation in San Marcos, Costa Rica

San Marcos experiences the highest level of ultraviolet (UV) radiation in March, April and May, when the maximum UV index can reach values of 15 - 16, which corresponds to the Extreme category of sun exposure. January, November and December are in the Extreme exposure category. In these months, the maximum values of the UV index do not exceed 12. For more detailed information, check out our hourly San Marcos UV Index data.

Average daily maximum UV levels by month for San Marcos. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
 JanFebMarAprMayJunJulAugSepOctNovDec
UV Index (month maximum)121415161514151414141211