Last updated: August 23, 2025
In September, the average temperature in San Francisco, Guatemala is a warm 28°C (82°F). While you can expect temperatures to dip to a minimum of 22°C (72°F), be prepared for sweltering highs reaching up to 38°C (101°F). During this month, precipitation averages 215 mm (8.4 in) across 24 days, contributing to an overall average humidity of 77%. Be ready for a mix of heat and occasional rain!
In September in San Francisco, the average temperature is 28°C (82°F), with maximums reaching up to 38°C (101°F) and minimums dropping as low as 22°C (72°F). This makes it an ideal destination for travelers seeking warm weather and plenty of sunshine.
In San Francisco in September, the total precipitation amount is 215 mm (8.4 in) spread over 24 days.
In San Francisco in September humidity is 77%. With an average temperature of 28°C (82°F), this humidity feels like a warm, enveloping blanket that can make outdoor activities sticky and exhausting, but also offers a lush vibrancy to the landscape, perfect for enjoying leisurely strolls in the early morning or late afternoon.
In San Francisco in September, the maximum UV index reaches 13, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to take protective measures. For detailed information, you can check the Hourly UV Index in San Francisco.
UV Risk Categories
Weather in San Francisco varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in San Francisco, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 24°C (75°F) | 43 mm (1.7 inches) | 84% | very high |
| February Weather | 25°C (78°F) | 23 mm (0.9 inches) | 73% | extreme |
| March Weather | 27°C (81°F) | 31 mm (1.2 inches) | 59% | extreme |
| April Weather | 30°C (87°F) | 40 mm (1.6 inches) | 52% | extreme |
| May Weather | 31°C (87°F) | 104 mm (4.1 inches) | 53% | extreme |
| June Weather | 28°C (83°F) | 247 mm (9.7 inches) | 55% | extreme |
| July Weather | 28°C (83°F) | 136 mm (5.4 inches) | 61% | extreme |
| August Weather | 28°C (83°F) | 158 mm (6.2 inches) | 71% | extreme |
| September Weather | 28°C (82°F) | 215 mm (8.4 inches) | 77% | extreme |
| October Weather | 27°C (80°F) | 200 mm (7.9 inches) | 78% | extreme |
| November Weather | 25°C (77°F) | 110 mm (4.3 inches) | 82% | very high |
| December Weather | 24°C (75°F) | 55 mm (2.2 inches) | 86% | very high |