Climate almanac
Diamond Bar
California, United States · 34.03°, -117.81°
What is the weather like in Diamond Bar in September?
In September, Diamond Bar is typically 86°F (30°C) during the day and 64°F (18°C) at night. The month brings about 0.3 in (9 mm) of precipitation in total.
- Average high86°F (30°C)
- Average low64°F (18°C)
- Precipitation0.3 in (9 mm)
- Clear or mostly clear days25
- Based on2016-2025 daily ERA5 reanalysis data (10-year normals)