Denver weather in September: Denver, Colorado: normal highs, lows, rain and records for September
Denver in September has a normal high of 80°F and a normal low of 50°F, a daily mean of 65°F, falling from 85°F on the 1st to 73°F by the 30th. Measurable precipitation falls on 6 days in a normal September, 1.35 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 26°C and low of 10°C, 34 mm of precipitation in September.
- NOAA stationDenver International Airport
- Station IDUSW00003017
- Location39.83°N 104.66°W
- Elevation5,414 ft (1,650 m)
- From the center13 miles
- Population729,019
- Jan 45° 19°
- Feb 46° 20°
- Mar 56° 28°
- Apr 62° 34°
- May 71° 44°
- Jun 83° 53°
- Jul 90° 60°
- Aug 88° 58°
- Sep 80° 50°
- Oct 65° 37°
- Nov 53° 26°
- Dec 44° 18°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Denver in September?
The normal high is 80°F and the normal low 50°F, for a daily mean of 64.8°F. September is 8.1°F cooler than August and 13.7°F warmer than October. September is the 4th warmest month of the year in Denver and the 6th wettest. Across the month the normal high falls 12°F, from 85°F on September 1 to 73°F on September 30. From one year to the next September's mean temperature typically moves about 2.8°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 62°F and 68°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 21%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 85°F | 55°F | 21% | 9% |
| September 8 | 83°F | 53°F | 20% | 9% |
| September 15 | 80°F | 51°F | 20% | 9% |
| September 22 | 77°F | 48°F | 19% | 9% |
| September 30 | 73°F | 44°F | 18% | 9% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 85°F | 55°F | 21% | 9% | 13 h 10 min |
| September 2 | 85°F | 55°F | 21% | 9% | 13 h |
| September 3 | 84°F | 54°F | 21% | 9% | 13 h |
| September 4 | 84°F | 54°F | 21% | 9% | 13 h |
| September 5 | 84°F | 54°F | 21% | 9% | 13 h |
| September 6 | 83°F | 54°F | 20% | 9% | 12 h 50 min |
| September 7 | 83°F | 53°F | 20% | 9% | 12 h 50 min |
| September 8 | 83°F | 53°F | 20% | 9% | 12 h 50 min |
| September 9 | 83°F | 53°F | 20% | 9% | 12 h 50 min |
| September 10 | 82°F | 52°F | 20% | 9% | 12 h 40 min |
| September 11 | 82°F | 52°F | 20% | 9% | 12 h 40 min |
| September 12 | 81°F | 52°F | 20% | 9% | 12 h 40 min |
| September 13 | 81°F | 51°F | 20% | 9% | 12 h 40 min |
| September 14 | 81°F | 51°F | 20% | 9% | 12 h 30 min |
| September 15 | 80°F | 51°F | 20% | 9% | 12 h 30 min |
| September 16 | 80°F | 50°F | 20% | 9% | 12 h 30 min |
| September 17 | 79°F | 50°F | 20% | 9% | 12 h 30 min |
| September 18 | 79°F | 49°F | 20% | 9% | 12 h 20 min |
| September 19 | 79°F | 49°F | 20% | 9% | 12 h 20 min |
| September 20 | 78°F | 49°F | 19% | 9% | 12 h 20 min |
| September 21 | 78°F | 48°F | 19% | 9% | 12 h 20 min |
| September 22 | 77°F | 48°F | 19% | 9% | 12 h 10 min |
| September 23 | 77°F | 47°F | 19% | 9% | 12 h 10 min |
| September 24 | 76°F | 47°F | 19% | 9% | 12 h 10 min |
| September 25 | 76°F | 46°F | 19% | 9% | 12 h 10 min |
| September 26 | 75°F | 46°F | 19% | 9% | 12 h |
| September 27 | 75°F | 45°F | 19% | 9% | 12 h |
| September 28 | 74°F | 45°F | 18% | 9% | 12 h |
| September 29 | 74°F | 45°F | 18% | 9% | 11 h 50 min |
| September 30 | 73°F | 44°F | 18% | 9% | 11 h 50 min |
- Normal high
- 80°FSeptember average
- Normal low
- 50°FSeptember average
- Precipitation
- 1.35 inmonth total
- Days with precipitation
- 60.01 inch or more
- Days at 90°F or more
- 4
- Nights at 32°F or colder
- 1
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 25
- Days at 80°F or more
- 18
- Sunshine
- 85%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00003017; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Denver in September?
On a given September day the chance of 0.01 inch or more is 20% on average, highest around September 1 (21%). In all, 1.35 in falls on 6 days of a normal September.
In a normal September in Denver, 4 days reach 90°F and 1 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00003017.
How humid and windy is Denver in September?
At 3 p.m. the normal temperature is 71°F with 24% relative humidity and a dew point of 32°F; at 6 a.m. it is 47°F with 63% humidity. The wind averages 9.4 mph, most often from the northeast in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 47°F | 35°F | 63% | 8.8 mph | – |
| 9 a.m. | 60°F | 36°F | 41% | 8.8 mph | – |
| noon | 68°F | 33°F | 27% | 8.6 mph | – |
| 3 p.m. | 71°F | 32°F | 24% | 10.3 mph | – |
| 6 p.m. | 61°F | 35°F | 37% | 9.5 mph | – |
| 9 p.m. | 54°F | 35°F | 49% | 9.4 mph | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00003017. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Denver?
The warmest September temperature on Denver's official record (since 1872) is 101°F, on September 5, 2020; the coldest is 17°F, on September 29, 1985. The wettest September brought 5.61 in (2013); the snowiest, 17.2 inches (1971).
The September mean against the 1991-2020 normal of 64.8°F: 2021 68.8°F (+4.0), 2022 69.0°F (+4.2), 2023 68.0°F (+3.2), 2024 70.0°F (+5.2), 2025 64.7°F (−0.1), 2026 69.2°F (+4.4). 5 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 68.8°F | +4.0°F | 0.28 in |
| 2022 | 69.0°F | +4.2°F | 1.25 in |
| 2023 | 68.0°F | +3.2°F | 0.67 in |
| 2024 | 70.0°F | +5.2°F | 1.24 in |
| 2025 | 64.7°F | −0.1°F | 1.76 in |
| 2026 | 69.2°F | +4.4°F | 2.23 in |
Source: records: ACIS, NWS threaded record DENthr; recent months: ACIS, station USW00003017. Records and recent months use complete months only.
How does September in Denver compare across Colorado?
Across the 125 places PlainClimate covers in Colorado, September normal highs run from 62°F in Leadville to 86°F in Lamar; Denver's is 80°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.