Last updated: March 2, 2024
The weather in South San Francisco, United States, during September is characterized by an average temperature of 17°C (63°F). Highs can soar to 28°C (82°F), while lows may dip to 12°C (53°F). Typically, the humidity level in South San Francisco throughout September hovers around 86%.
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Average temperature
Maximum temperature
Humidity
In September, South San Francisco averages 2 mm (0.1 inches) of rainfall, typically over the course of 0 rainy days. The month enjoys an average of 12 hours 22 minutes of daylight, with the sun shining for approximately 9 hours 57 minutes each day. Additionally, there is a 51% probability of sunny days during this period.
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Chance of sun
In September, the UV Index in South San Francisco reaches a maximum of 9, indicating a level of VeryHigh exposure. The most intense UV radiation typically occurs between 13:00 and 15:00, during which unprotected skin may burn in as little as 15 minutes.
| 07:00 | 08:00 | 09:00 | 10:00 | 11:00 | 12:00 | 13:00 | 14:00 | 15:00 | 16:00 | 17:00 | 18:00 | 19:00 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UVI | 1 | 1 | 2 | 4 | 6 | 8 | 9 | 8 | 6 | 4 | 2 | 1 | 1 |
| Exposure | Low | Moderate | High | VeryHigh | High | Moderate | Low | ||||||
| Time to burn | 45 min | 30 min | 25 min | 15 min | 25 min | 30 min | 45 min | ||||||