Last updated: March 2, 2024
The weather in Grand Coulee, United States, during September is characterized by an average temperature of 17°C (62°F). Highs can soar to 31°C (88°F), while lows may dip to 5°C (41°F). Typically, the humidity level in Grand Coulee throughout September hovers around 60%.
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Average temperature
Maximum temperature
Humidity
In September, Grand Coulee averages 24 mm (1.0 inches) of rainfall, typically over the course of 3 rainy days. The month enjoys an average of 12 hours 30 minutes of daylight, with the sun shining for approximately 9 hours 41 minutes each day. Additionally, there is a 54% probability of sunny days during this period.
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Chance of sun
In September, the UV Index in Grand Coulee reaches a maximum of 7, indicating a level of High exposure. The most intense UV radiation typically occurs between 12:00 and 14:00, during which unprotected skin may burn in as little as 25 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 | 7 | 7 | 6 | 5 | 3 | 2 | 1 | 1 |
| Exposure | Low | Moderate | High | Moderate | Low | ||||||||
| Time to burn | 45 min | 30 min | 25 min | 30 min | 45 min | ||||||||