Climate Overview
The climate in San Mateo is hot. The average annual temperature is 29°C and approximately 990mm of precipitation falls per year. November is the wettest month, receiving around 164mm of rainfall. San Mateo sits near the equator, so seasonal temperature differences are minimal throughout the year.
Temperature
San Mateo sees moderate temperature variation throughout the year, ranging from 23°C to 38°C. March is the hottest month, with daytime highs reaching 38°C and an average of 30°C. December is the coolest month, with minimum temperatures around 23°C and an average of 28°C. On average, daily temperatures fluctuate by about 11°C between overnight lows and afternoon highs. The sharpest temperature change occurs between October and November, with a 2°C shift in average temperatures.
Precipitation
San Mateo is a moderately rainy area, receiving approximately 990mm of precipitation annually, which averages out to around 83mm per month. The wettest month is November, averaging 164mm of rainfall. September and May also tend to see above-average precipitation. The driest month is January, with just 1mm. That's 163mm less than November, 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 Mateo 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 March, averaging 3km/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. There is moderate seasonal variation in wind speed, with a 1km/h gap between the calmest and windiest months.
Seasons
64 days until Autumn
It is currently summer in San Mateo, which began on June 21, 2026. San Mateo sits near the equator, so the traditional four-season cycle is less pronounced — temperatures remain relatively stable year-round. The warmest period peaks in March at around 38°C, while the coldest stretch bottoms out in December near 23°C. Autumn is next, beginning on September 23, 2026 — 64 days from now.
Spring
Temperatures range from 25 to 38°C. Precipitation is moderate at around 239mm for the season, averaging 80mm per month. Winds are generally light, averaging 2km/h. An umbrella or waterproof jacket is advisable as spring showers are frequent.
Summer
Temperatures range from 24 to 35°C. Rainfall is heavy, totalling around 311mm across the season with a monthly average of 104mm. Winds are generally light, averaging 2km/h. Light, breathable clothing is ideal — perfect conditions for outdoor activities.
Autumn
Temperatures range from 24 to 36°C. Rainfall is heavy, totalling around 390mm across the season with a monthly average of 130mm. Winds are generally light, averaging 2km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.
Winter
Temperatures range from 23 to 37°C. Rainfall is relatively light, with around 50mm over the season and a monthly average of 17mm. Winds are generally light, averaging 2km/h. A light jacket or sweater is usually sufficient, though cooler evenings may call for an extra layer.
Monthly Climate Data
The table below shows monthly climate averages for San Mateo 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.