Aspen, CO weather in September
Expect mild weather with frequent rain in Aspen in September, with highs near 67°F and lows near 40°F. Rain or snow falls on about 10 days. Snowfall averages about 1.0 in. Great for outdoor plans.
- Normal high
- 67°F
- Normal low
- 40°F
- Wet days
- 10
- 1.9 in total
- Snowfall
- 1.0 in
- normal snowfall
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 71°F | 62°F |
| Normal low | 44°F | 35°F |
| Chance of a wet day | 36% | 31% |
| Sunrise / sunset | 6:36 am / 7:38 pm | 7:02 am / 6:52 pm |
| Daylight | 13.0 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Mountain Time).
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F22 of 30
- Hot dayshigh 90°F or more0 of 30
- Muggy daysdaily mean dew point 65°F or more0 of 30
- Wet daysat least 0.01 in of rain or melted snow10 of 30
- Notable rainat least 0.10 in6 of 30
- Freezing nightslow 32°F or below4 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain and snow in September
Normal precipitation is 1.9 in; a dry September brings about 1.3 in and a wet one about 2.6 in (25th and 75th percentiles). About 1 day brings half an inch or more. Normal snowfall is 1.0 in.
How September varies from year to year
- Warmest September, 1991-20201998: average high 75°F
- Coolest September1996: average high 64°F
- Wettest September2013: 4.3 in
- Driest September2019: 0.4 in
- Highest reading86°F (September 5, 1998)
- Lowest reading18°F (September 28, 1996)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 73°F | 67°F | 55°F |
| Normal low | 47°F | 40°F | 30°F |
| Wet days | 13 | 10 | 9 |
| Comfortable days | 25 | 22 | 9 |
| Daylight | 13.7 h | 12.4 h | 11.2 h |
Highs change by -6°F from August and -12°F into October.
Nearby alternatives in September
- Warmer: Steamboat Springs, CO89 mi · high 74°F · 10 wet days
- Drier: Lakewood, CO99 mi · high 76°F · 7 wet days
- Cooler: Breckenridge, CO46 mi · high 62°F · 10 wet days
How Aspen ranks in September
- Normal high365th warmest of 378 cities; 15th of 17 in Colorado
- Wet days310th driest of 378
- Comfortable days9th most of 342
What to pack for Aspen in September
- A warm jacket – lows near 40°F, highs near 67°F
- Layers – afternoons near 67°F but nights near 40°F
- A rain jacket or umbrella – rain or snow on about 10 days
Frost in September
The first fall frost typically comes around Sep 23; in 1 year in 10 it comes before Sep 11. All frost dates for Aspen.
Heating and cooling
September has 347 heating degree days and 0 cooling degree days (base 65°F), 4% of the year's total heating and cooling demand.
Questions
How cold is Aspen in September?
The normal high is 67°F and the normal low is 40°F. From 1991 to 2020 the coldest September reading was 18°F (most recently on September 28, 1996).
Does it rain a lot in Aspen in September?
About 10 days in September have at least 0.01 in of precipitation, and the normal total is 1.9 in. The wettest September in 1991-2020 was in 2013 (4.3 in); the driest was in 2019 (0.4 in).
Does it snow in Aspen in September?
Yes. Normal snowfall in September is 1.0 in.
Is September a good time to visit Aspen?
September ranks 4th of 12 months on our comfort score for Aspen (78 out of 100). It has about 22 comfortable days. The best month is June.
Where the numbers come from
- Temperature, rain, snowfall and snow depth: Aspen 1SW (USC00050372), 1.2 mi WSW of the city center, 8,175 ft (285 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Frost dates: Aspen Pitkin Co Airport (USW00093073), 3.5 mi NW of the city center, 7,720 ft (170 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Eagle Co Regional Airport (724675-23063), 32 mi N of the city center, 6,497 ft (1,393 ft lower than the city). Hourly observations, 1991-2020.
- Not available for this location: humidity and wind by hour and cloud cover (no station close enough or similar enough in elevation).