Denver, Colorado weather in September

Averages from 2021–2025 (150 days of record).

Average high: 83°F
Average low: 52°F
Rainy days: ~5 per month
Total precipitation: 1.0 in
Warmest recorded: 98°F
Coldest recorded: 40°F

Expect September days in Denver, Colorado to top out around 83°F and cool to about 52°F overnight, with roughly 5 days of measurable rain across the month. In recent years September has ranged from 40°F to 98°F.

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Current Denver, Colorado forecast → · Historical data by Open-Meteo (ERA5).