Last updated: June 24, 2025
In Bellevue, United States, the average temperature in September hovers around 13°C (56°F), offering a mild climate. However, be prepared for a range of temperatures—with minimums plummeting to -6°C (21°F) and maximums soaring to 32°C (91°F). Expect 21 mm (0.8 in) of precipitation spread over 4 days, contributing to an average humidity level of 46%.
In September in Bellevue, the average temperature is 13°C (56°F). Maximum temperatures can reach 32°C (91°F), while minimums can drop to as low as -6°C (21°F). It's advisable to pack accordingly to enjoy a variety of weather conditions during your travels.
In Bellevue in September, the precipitation amount is 21 mm (0.8 in) over a span of 4 days.
In Bellevue in September, humidity is 46%. With an average temperature of 13°C (56°F), this humidity feels like a refreshing embrace, making it comfortable for traveling while allowing for enjoyable outdoor explorations without the heaviness often associated with higher humidity.
In Bellevue in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Bellevue.
UV Risk Categories
Weather in Bellevue varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Bellevue, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -7°C (20°F) | 58 mm (2.3 inches) | 91% | moderate |
| February Weather | -6°C (22°F) | 80 mm (3.1 inches) | 92% | moderate |
| March Weather | -1°C (30°F) | 49 mm (1.9 inches) | 85% | very high |
| April Weather | 3°C (38°F) | 43 mm (1.7 inches) | 76% | very high |
| May Weather | 8°C (47°F) | 52 mm (2.0 inches) | 66% | extreme |
| June Weather | 15°C (58°F) | 25 mm (1.0 inches) | 62% | extreme |
| July Weather | 20°C (68°F) | 5 mm (0.2 inches) | 53% | extreme |
| August Weather | 19°C (66°F) | 17 mm (0.7 inches) | 42% | very high |
| September Weather | 13°C (56°F) | 21 mm (0.8 inches) | 46% | very high |
| October Weather | 5°C (41°F) | 34 mm (1.3 inches) | 64% | high |
| November Weather | -1°C (30°F) | 43 mm (1.7 inches) | 83% | moderate |
| December Weather | -7°C (20°F) | 45 mm (1.8 inches) | 87% | moderate |