Climate almanac
Boulder
Colorado, United States · 40.01°, -105.27°
What is the weather like in Boulder in September?
In September, Boulder is typically 76°F (25°C) during the day and 47°F (8°C) at night. The month brings about 1.8 in (45 mm) of precipitation in total. Snowfall averages about 1.0 in (24 mm) over the month.
- Average high76°F (25°C)
- Average low47°F (8°C)
- Precipitation1.8 in (45 mm)
- Clear or mostly clear days19
- Snowfall1.0 in (24 mm)
- Based on2016-2025 daily ERA5 reanalysis data (10-year normals)