Aspen in September
In September, Aspen averages 21°C (70°F) during the day and 5°C (41°F) at night, with around 13 days of rain (37 mm total).
ShoulderConditions are comfortable for sightseeing without being sweltering. Plan for unsettled weather and bring rain gear.
It's peak hurricane season in Aspen during September. Travel is possible but expect storm risk, possible flight disruption, and generally lower travel insurance coverage.
How September compares to the rest of the year in Aspen
September is in the middle of the year for warmth in Aspen (4th of 12) and one of the driest months (10th of 12). Daytime temperature runs 9°C above the annual average (12°C). September runs 3°C cooler than August (25°C) and cools 9°C in October (13°C).
September sunrise & sunset in Aspen
Times shown for Aspen local time (America/Denver), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in Aspen — September
Golden-hour and blue-hour windows for the 15th of September, in Aspen's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Aspen in September
Travel writers usually only tell you when to go. Here's when to book flights and lodging for the best mix of price and availability, based on September's tier (Shoulder) and Aspen's popularity.
Crowds & pricing — September in Aspen
Aspen is in a shoulder season month — fewer crowds, slightly lower prices, and a calmer atmosphere than peak weeks. Most major sights stay open with normal hours, though a handful of seasonal restaurants or boat trips may run reduced schedules. Many regulars consider these months the best time to visit because you trade a small amount of weather reliability for a much more pleasant on-the-ground experience.
Why this tier: excellent tourism weather peak hazard season (1 active)
Sun & mosquito risk — September in Aspen
UV is a clear-sky sea-level estimate — clouds, altitude, and reflective surfaces (snow, water) shift it ±30%. Mosquito risk is climate-derived only; for current disease advisories (dengue, malaria, zika) check the CDC or WHO travel pages before your trip.
Aspen in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 0°C / 32°F | -11°C / 11°F | 55 mm | 16 | — |
| February | 1°C / 34°F | -10°C / 14°F | 65 mm | 17 | — |
| March | 5°C / 41°F | -7°C / 19°F | 71 mm | 18 | — |
| April | 9°C / 48°F | -4°C / 25°F | 67 mm | 18 | — |
| May | 14°C / 57°F | -1°C / 31°F | 63 mm | 21 | — |
| June | 22°C / 72°F | 4°C / 39°F | 30 mm | 15 | — |
| July | 26°C / 78°F | 9°C / 48°F | 41 mm | 20 | — |
| August | 25°C / 76°F | 8°C / 46°F | 39 mm | 18 | — |
| September | 21°C / 70°F | 5°C / 41°F | 37 mm | 13 | — |
| October | 13°C / 55°F | -3°C / 27°F | 51 mm | 12 | — |
| November | 5°C / 41°F | -10°C / 14°F | 56 mm | 13 | — |
| December | 0°C / 33°F | -13°C / 9°F | 71 mm | 15 | — |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Aspen in September →
Frequently asked questions
How hot is Aspen in September?
In September, Aspen averages a high of 21°C (70°F) and a low of 5°C (41°F) — generally mild and pleasant.
Does it rain a lot in Aspen in September?
September can be fairly wet in Aspen, with about 13 rainy days on average.
Is September a good time to visit Aspen?
September is mild and pleasant. It suits travelers who are comfortable with mild and pleasant weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Aspen in September?
Pack light layers for warm days and cooler evenings, plus a compact umbrella or rain jacket. See the full September packing list for Aspen for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.