Denver in September
In September, Denver averages 27°C (81°F) during the day and 11°C (52°F) at night, with around 9 days of rain (23 mm total).
ShoulderConditions are warm and beach-friendly. Occasional showers are likely but won't dominate.
It's peak hurricane season in Denver 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 Denver
September is in the middle of the year for warmth in Denver (4th of 12) and moderately rainy compared to the rest of the year (9th of 12). Daytime temperature runs 9°C above the annual average (18°C). September runs 3°C cooler than August (30°C) and cools 9°C in October (18°C).
September sunrise & sunset in Denver
Times shown for Denver 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 Denver — September
Golden-hour and blue-hour windows for the 15th of September, in Denver's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Denver 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 Denver's popularity.
Crowds & pricing — September in Denver
Denver 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: comfortable tourism weather peak hazard season (1 active)
Sun & mosquito risk — September in Denver
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.
Denver in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 5°C / 41°F | -9°C / 16°F | 26 mm | 10 | — |
| February | 6°C / 43°F | -9°C / 15°F | 23 mm | 11 | — |
| March | 12°C / 53°F | -4°C / 24°F | 47 mm | 12 | — |
| April | 16°C / 61°F | 0°C / 33°F | 48 mm | 14 | — |
| May | 20°C / 68°F | 6°C / 42°F | 102 mm | 18 | — |
| June | 28°C / 83°F | 12°C / 54°F | 47 mm | 14 | — |
| July | 31°C / 88°F | 16°C / 60°F | 38 mm | 17 | — |
| August | 30°C / 86°F | 15°C / 58°F | 34 mm | 13 | — |
| September | 27°C / 81°F | 11°C / 52°F | 23 mm | 9 | — |
| October | 18°C / 65°F | 3°C / 37°F | 30 mm | 8 | — |
| November | 11°C / 52°F | -4°C / 26°F | 21 mm | 7 | — |
| December | 6°C / 43°F | -8°C / 18°F | 20 mm | 8 | — |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Denver in September →
Frequently asked questions
How hot is Denver in September?
In September, Denver averages a high of 27°C (81°F) and a low of 11°C (52°F) — generally warm.
Does it rain a lot in Denver in September?
September sees occasional rain in Denver, with about 9 rainy days on average.
Is September a good time to visit Denver?
September is warm. It suits travelers who are comfortable with warm weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Denver in September?
Pack lightweight, breathable clothing, sunglasses and sunscreen. See the full September packing list for Denver for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.