How warm is it in Aspen in September?

Daytime highs averaged 16.6 °C, night-time lows 1.8 °C. The highest value of the past 10 years was 26.1 °C (6 Sep 2022), the lowest -7.5 °C (9 Sep 2020).

How often does it rain in Aspen in September?

On average there were 7.9 rain days (at least 1 mm) with 34.4 mm of precipitation in total.

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Aspen weather in September: temperature & rain

Photo: Jeffrey Beall · CC BY 4.0

🇺🇸 Weather in Aspen in September

This is what the weather in Aspen (Colorado, USA) was like in September over the years 2017–2026.

Key facts at a glance

Prevailing weather: Sunny

Avg. daytime high

16.6 °C

14.7 °C – 18.1 °C

Avg. night-time low

1.8 °C

0.2 °C – 3.3 °C

Avg. rain days in period

7.9

26 % of days · ≥ 1.0 mm

Avg. precipitation in period

34.4 mm

14.8 mm – 58.3 mm

Avg. cloud cover

39 %

This data source has no sunshine hours – average cloud cover is shown instead.

Avg. sea temperature

–

No sea nearby – no sea temperature.

Extremes: Highest temperature 26.1 °C (6 Sep 2022) · Lowest temperature -7.5 °C (9 Sep 2020) · Avg. daily peak wind 12 km/h

Weather mix of all days

115Sunny
82Partly cloudy
12Cloudy
60Light rain
16Rain
3Snow

Summary

On average 16.6 °C during the day and 1.8 °C at night.
On average 7.9 rain days (Rain day = at least 1.0 mm of precipitation) with 34.4 mm of precipitation in total.
Prevailing weather: Sunny.
Warmest year: 2022 (avg. 18.1 °C), coolest: 2017 (avg. 14.7 °C).
Wettest year: 2026 (58.3 mm), driest: 2018 (14.8 mm).
Extremes: 26.1 °C on 6 Sep 2022 and -7.5 °C on 9 Sep 2020.

Overall values from all 10 years. How is this calculated?

Temperatures per year

Average over your travel period

Precipitation & rain days

Year by year

2026
Avg. max16.3°Avg. min3.3°
Rain days
18 Rain days
Precipitation
58.3 mm
Avg. cloud cover
–
Sea temperature
–
Max 21.6 °C · Min -0.6 °C
2025
Avg. max15.4°Avg. min1.1°
Rain days
9 Rain days
Precipitation
39.7 mm
Avg. cloud cover
53 % cloudy
Sea temperature
–
Max 21.3 °C · Min -4.0 °C
2024
Avg. max17.3°Avg. min1.7°
Rain days
5 Rain days
Precipitation
34.0 mm
Avg. cloud cover
32 % cloudy
Sea temperature
–
Max 21.3 °C · Min -4.3 °C
2023
Avg. max16.6°Avg. min1.7°
Rain days
7 Rain days
Precipitation
20.2 mm
Avg. cloud cover
35 % cloudy
Sea temperature
–
Max 22.3 °C · Min -3.9 °C
2022
Avg. max18.1°Avg. min2.9°
Rain days
8 Rain days
Precipitation
47.6 mm
Avg. cloud cover
36 % cloudy
Sea temperature
–
Max 26.1 °C · Min -3.0 °C
2021
Avg. max17.6°Avg. min3.2°
Rain days
8 Rain days
Precipitation
43.9 mm
Avg. cloud cover
38 % cloudy
Sea temperature
–
Max 24.3 °C · Min -4.5 °C
2020
Avg. max16.3°Avg. min0.2°
Rain days
3 Rain days
Precipitation
27.4 mm
Avg. cloud cover
34 % cloudy
Sea temperature
–
Max 24.0 °C · Min -7.5 °C
2019
Avg. max17.1°Avg. min1.5°
Rain days
5 Rain days
Precipitation
15.5 mm
Avg. cloud cover
40 % cloudy
Sea temperature
–
Max 25.3 °C · Min -5.0 °C
2018
Avg. max17.0°Avg. min1.7°
Rain days
5 Rain days
Precipitation
14.8 mm
Avg. cloud cover
36 % cloudy
Sea temperature
–
Max 20.4 °C · Min -3.7 °C
2017
Avg. max14.7°Avg. min0.6°
Rain days
11 Rain days
Precipitation
42.7 mm
Avg. cloud cover
46 % cloudy
Sea temperature
–
Max 23.4 °C · Min -6.5 °C

Frequently asked questions

How warm is it in Aspen in September?: Daytime highs averaged 16.6 °C, night-time lows 1.8 °C. The highest value of the past 10 years was 26.1 °C (6 Sep 2022), the lowest -7.5 °C (9 Sep 2020).
How often does it rain in Aspen in September?: On average there were 7.9 rain days (at least 1 mm) with 34.4 mm of precipitation in total.

Check your exact travel dates

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Data sources

Weather data: Data obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program
Reanalysis (weather model constrained by observations) on a coarse grid of about 50 km. Values represent a large area and can differ from local conditions, especially on islands, coasts and in mountains. Snow depth is the model value for the grid cell, not the depth on the slopes. No sunshine duration.
Reanalysis (weather model constrained by observations)
Reanalysis values represent a grid cell (approx. 25–50 km) and may differ from local measurements on coasts, islands and in mountains.
Sea temperature: MUR SST data were provided by JPL under support by NASA MEaSUREs program; accessed via NOAA CoastWatch ERDDAP
Daily multi-scale ultra-high resolution (≈ 1 km) analysis of satellite measurements (infrared, microwave) and in-situ data. Represents the foundation temperature below the daily warm surface layer. (Satellite and in-situ analysis)
Place search: Natural Earth (public domain) · GeoNames (CC BY 4.0) / OpenStreetMap (ODbL)