Last updated: August 27, 2025
In September, the average temperature in San Mateo, Peru hovers around 3°C (37°F), making it a chilly time of year. Expect temperatures to dip as low as -7°C (20°F) and reach a maximum of 12°C (53°F). With 120 mm (4.7 in) of precipitation falling over 24 days, it's wise to keep an umbrella handy. Average humidity rests at a comfortable 40%, ensuring that even the cold feels crisp rather than damp.
In September in San Mateo, the average temperature is 3°C (37°F), with maximums reaching up to 12°C (53°F) and minimums plunging as low as -7°C (20°F). This chilly weather makes it essential to pack warm clothing if you're planning to visit.
In San Mateo in September, the total precipitation amount is 120 mm (4.7 in) spread over 24 days.
In San Mateo in September, humidity is 40%. With an average temperature of 3°C (37°F), this humidity feels like a brisk, chilly air that sharpens the senses, making it ideal for invigorating strolls but requiring layering for comfort during outdoor explorations.
In San Mateo in September, the maximum UV index reaches an alarming 17, which falls under the extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to stay protected. For more details on the hourly UV index in San Mateo, you can check Hourly UV Index in San Mateo.
UV Risk Categories
Weather in San Mateo varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in San Mateo, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 3°C (38°F) | 220 mm (8.7 inches) | 91% | extreme |
| February Weather | 3°C (39°F) | 251 mm (9.9 inches) | 90% | extreme |
| March Weather | 3°C (38°F) | 291 mm (11.5 inches) | 91% | extreme |
| April Weather | 3°C (38°F) | 164 mm (6.5 inches) | 89% | extreme |
| May Weather | 3°C (37°F) | 124 mm (4.9 inches) | 85% | extreme |
| June Weather | 2°C (36°F) | 50 mm (2.0 inches) | 65% | extreme |
| July Weather | 2°C (35°F) | 44 mm (1.7 inches) | 47% | extreme |
| August Weather | 2°C (36°F) | 59 mm (2.3 inches) | 38% | extreme |
| September Weather | 3°C (37°F) | 120 mm (4.7 inches) | 40% | extreme |
| October Weather | 3°C (38°F) | 174 mm (6.8 inches) | 56% | extreme |
| November Weather | 4°C (39°F) | 232 mm (9.1 inches) | 76% | extreme |
| December Weather | 4°C (39°F) | 244 mm (9.6 inches) | 90% | extreme |