Monthly climate guide
Denver weather in September
With highs near 25°C (78°F) and lows around 10°C (49°F), September feels warm in Denver. Rainfall averages about 42 mm (fairly dry) and the sky is a mix of sun and cloud. Daytime highs are 4°C cooler than August and 8°C warmer than October.
What stands out in September
- In Denver, September is early autumn.
- Evenings cool off sharply: the daily range is around 16°C, so pack a layer.
- Denver is usually about 2°C warmer than Colorado Springs, 100 km away, in September.
- Temperatures are falling — expect highs around 8°C lower by October.
Avg high
25°C
78°F
Avg low
10°C
49°F
Rainfall
42 mm
fairly dry
Humidity
45%
relative
Sky
40%
cloud · a mix of sun and cloud
Denver weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 5°C / 41°F | -6°C / 20°F | 18 mm | 55% | 54% |
| February | 6°C / 42°F | -7°C / 19°F | 26 mm | 57% | 55% |
| March | 12°C / 53°F | -3°C / 26°F | 32 mm | 51% | 52% |
| April | 15°C / 59°F | -1°C / 31°F | 46 mm | 50% | 56% |
| May | 20°C / 68°F | 4°C / 39°F | 69 mm | 51% | 57% |
| June | 29°C / 83°F | 11°C / 52°F | 38 mm | 40% | 44% |
| July | 30°C / 86°F | 15°C / 58°F | 67 mm | 47% | 47% |
| August | 29°C / 84°F | 14°C / 56°F | 42 mm | 45% | 46% |
| September | 25°C / 78°F | 10°C / 49°F | 42 mm | 45% | 40% |
| October | 18°C / 64°F | 2°C / 35°F | 27 mm | 48% | 43% |
| November | 11°C / 52°F | -3°C / 27°F | 20 mm | 50% | 45% |
| December | 5°C / 41°F | -7°C / 20°F | 18 mm | 55% | 51% |
What to pack for September
- T-shirts plus a light layer for the evening
- Comfortable trainers or sandals for long walks
- An extra layer — evenings are noticeably cooler than afternoons
- A small travel umbrella, just in case
Is September a good time to visit Denver?
Compare the months in the chart above to find your ideal window.
Best time to visit Denver →Other United States cities in September
Cite or embed this data
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Denver weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/usa/denver/september
<a href="https://weathercompare.eu/weather/usa/denver/september">Denver weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/usa/denver" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="Denver weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/usa/denver/september">Denver weather in September</a> – WeatherCompare</p>
Denver in September: quick answers
Is September a good time to visit Denver?
Yes. September is one of the best months for Denver, with highs around 25°C and about 42 mm of rain.
How warm is Denver in September?
Average highs are about 25°C (78°F) and average lows about 10°C (49°F), based on 10 years of daily data.
Does it rain a lot in Denver in September?
Denver typically gets around 42 mm of rain in September — fairly dry.
Figures are long-term averages for the area around Denver (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.