Climate Overview
The climate in San Marcos is temperate. The average annual temperature is 15°C and approximately 1075mm of precipitation falls per year. September is the wettest month, receiving around 199mm of rainfall. San Marcos is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: May, April, March. The coldest months are January, December, February, when temperatures can drop to 4°C.
Temperature
Temperatures in San Marcos vary considerably across the year, with a 22°C difference between the coldest and warmest months. The warmest month is May, when average highs reach 26°C and the mean temperature sits around 18°C. January is the coolest month, with minimum temperatures around 4°C and an average of 11°C. On average, daily temperatures fluctuate by about 13°C between overnight lows and afternoon highs. The sharpest temperature change occurs between January and February, with a 2°C shift in average temperatures.
Precipitation
San Marcos is a moderately rainy area, receiving approximately 1075mm of precipitation annually, which averages out to around 90mm per month. The wettest month is September, averaging 199mm of rainfall. June and August also tend to see above-average precipitation. The driest month is December, with just 9mm. That's 190mm less than September, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic.
Wind
San Marcos is relatively calm, with an average annual wind speed of 2km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is October, averaging 2km/h, though still comfortable for most outdoor activities. The calmest conditions occur in July, with average winds dropping to 2km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 0km/h between the calmest and windiest months.
Seasons
92 days until Autumn
It is currently summer in San Marcos, which began on June 21, 2026. San Marcos is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in May at around 26°C, while the coldest stretch bottoms out in January near 4°C. Autumn is next, beginning on September 23, 2026 — 92 days from now.
Spring
Temperatures range from 8 to 26°C. Rainfall is relatively light, with around 143mm over the season and a monthly average of 48mm. Winds are generally light, averaging 2km/h. Light layers work well as temperatures warm through the season — a great time to be outdoors.
Summer
Temperatures range from 11 to 24°C. Rainfall is heavy, totalling around 566mm across the season with a monthly average of 189mm. Winds are generally light, averaging 2km/h. Comfortable clothing with a light layer for cooler evenings is all you need.
Autumn
Temperatures range from 7 to 21°C. Rainfall is heavy, totalling around 323mm across the season with a monthly average of 108mm. Winds are generally light, averaging 2km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.
Winter
Temperatures range from 4 to 22°C. Precipitation is minimal, with only around 43mm for the entire season. Winds are generally light, averaging 2km/h. A light jacket or sweater is usually sufficient, though cooler evenings may call for an extra layer.
Best Time to Visit
The best time to visit San Marcos is during March, April and May, when the weather is most comfortable for travellers. During these months, average temperatures hover around 17°C with modest rainfall averaging 48mm per month. By contrast, January can be quite cold with temperatures dropping to 4°C. A light rain jacket is recommended, though showers are generally brief and shouldn't disrupt your plans.
Monthly Climate Data
The table below shows monthly climate averages for San Marcos based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.
