Colorado weather in September
September is one of the best months to visit Colorado: highs of 24°C (76°F) and about 36 mm (1.4 in) of rain on average. Nights average 8°C (47°F) and cloud cover 38% (NASA POWER, 2001–2025 averages). It is the 6th wettest month of the year and the 4th warmest. Compared with August, it is cooler and drier; October brings highs of 17°C (62°F) and 30 mm (1.2 in) of rain.
Figures are long-term averages for Denver, the largest city in Colorado. See below for other places.
Is September a good time to visit Colorado?
best month Weather score 86/100.
Yes. September is one of the best months for weather in Colorado.
Does it rain a lot in Colorado in September?
No, it is usually dry: about 36 mm (1.4 in) falls in an average September. It is the 6th wettest month of the year.
How warm is Colorado in September?
Days average 24°C (76°F) and nights 8°C (47°F).
Colorado weather by month
| Month | High | Low | Rain | Cloud | Weather |
|---|---|---|---|---|---|
| January | 4°C (40°F) | -7°C (19°F) | 17 mm | 56% | least pleasant |
| February | 5°C (41°F) | -8°C (18°F) | 21 mm | 57% | least pleasant |
| March | 10°C (51°F) | -4°C (25°F) | 34 mm | 55% | least pleasant |
| April | 15°C (59°F) | -1°C (31°F) | 51 mm | 55% | fair |
| May | 21°C (69°F) | 4°C (40°F) | 58 mm | 56% | best |
| June | 28°C (83°F) | 11°C (51°F) | 42 mm | 46% | best |
| July | 30°C (86°F) | 15°C (58°F) | 62 mm | 47% | best |
| August | 28°C (83°F) | 13°C (55°F) | 52 mm | 47% | best |
| September | 24°C (76°F) | 8°C (47°F) | 36 mm | 38% | best |
| October | 17°C (62°F) | 1°C (34°F) | 30 mm | 44% | best |
| November | 10°C (49°F) | -4°C (25°F) | 18 mm | 48% | least pleasant |
| December | 4°C (39°F) | -8°C (18°F) | 19 mm | 56% | least pleasant |
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis). Page updated . How we rate months
Weather across Colorado in September
Weather can differ a lot within Colorado: coasts, hills and mountains each have their own climate.
| Place | High | Low | Rain | Weather |
|---|---|---|---|---|
| Denver | 24°C (76°F) | 8°C (47°F) | 36 mm | best |
| Colorado Springs | 23°C (73°F) | 7°C (44°F) | 35 mm | best |
| Aurora | 24°C (76°F) | 8°C (47°F) | 36 mm | best |
| Fort Collins | 26°C (78°F) | 10°C (49°F) | 37 mm | best |
| Lakewood | 24°C (76°F) | 8°C (47°F) | 36 mm | best |
| Thornton | 26°C (78°F) | 10°C (50°F) | 36 mm | best |
| Westminster | 26°C (78°F) | 10°C (50°F) | 36 mm | best |
| Arvada | 26°C (78°F) | 10°C (50°F) | 36 mm | best |
| Centennial | 24°C (76°F) | 8°C (47°F) | 36 mm | best |
| Pueblo | 27°C (81°F) | 11°C (52°F) | 29 mm | best |
| Greeley | 26°C (78°F) | 10°C (49°F) | 37 mm | best |
| Boulder | 26°C (78°F) | 10°C (50°F) | 36 mm | best |