Last updated: March 2, 2024
The weather in Walnut Creek, United States, during September is characterized by an average temperature of 20°C (68°F). Highs can soar to 32°C (90°F), while lows may dip to 8°C (47°F). Typically, the humidity level in Walnut Creek throughout September hovers around 77%.
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Average temperature
Maximum temperature
Humidity
In September, Walnut Creek averages 105 mm (4.2 inches) of rainfall, typically over the course of 10 rainy days. The month enjoys an average of 12 hours 24 minutes of daylight, with the sun shining for approximately 9 hours 20 minutes each day. Additionally, there is a 54% probability of sunny days during this period.
Precipitation
Rainy days
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Chance of sun
In September, the UV Index in Walnut Creek reaches a maximum of 8, 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 | 3 | 5 | 7 | 8 | 8 | 6 | 5 | 3 | 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 | ||||||