St. Louis in September
In September, St. Louis averages 27°C (81°F) during the day and 17°C (63°F) at night, with around 13 days of rain (112 mm total).
ShoulderConditions are warm and beach-friendly. Plan for unsettled weather and bring rain gear.
It's peak hurricane season in St. Louis 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 St. Louis
September is in the middle of the year for warmth in St. Louis (4th of 12) and one of the driest months (10th of 12). Daytime temperature runs 8°C above the annual average (19°C). September runs 2°C cooler than August (30°C) and cools 7°C in October (20°C).
September sunrise & sunset in St. Louis
Times shown for St. Louis local time (America/Chicago), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in St. Louis — September
Golden-hour and blue-hour windows for the 15th of September, in St. Louis's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — St. Louis 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 St. Louis's popularity.
Crowds & pricing — September in St. Louis
St. Louis 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 St. Louis
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.
St. Louis in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 5°C / 41°F | -4°C / 25°F | 74 mm | 13 | — |
| February | 7°C / 45°F | -4°C / 26°F | 72 mm | 13 | — |
| March | 13°C / 56°F | 3°C / 37°F | 133 mm | 16 | — |
| April | 19°C / 66°F | 8°C / 46°F | 132 mm | 16 | — |
| May | 25°C / 76°F | 14°C / 58°F | 130 mm | 20 | — |
| June | 30°C / 86°F | 20°C / 67°F | 137 mm | 17 | — |
| July | 31°C / 87°F | 21°C / 70°F | 152 mm | 17 | — |
| August | 30°C / 85°F | 20°C / 69°F | 140 mm | 18 | — |
| September | 27°C / 81°F | 17°C / 63°F | 112 mm | 13 | — |
| October | 20°C / 68°F | 10°C / 51°F | 106 mm | 14 | — |
| November | 12°C / 54°F | 3°C / 37°F | 77 mm | 12 | — |
| December | 8°C / 46°F | -1°C / 31°F | 76 mm | 10 | — |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for St. Louis in September →
Frequently asked questions
How hot is St. Louis in September?
In September, St. Louis averages a high of 27°C (81°F) and a low of 17°C (63°F) — generally warm.
Does it rain a lot in St. Louis in September?
September can be fairly wet in St. Louis, with about 13 rainy days on average.
Is September a good time to visit St. Louis?
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 St. Louis in September?
Pack lightweight, breathable clothing, sunglasses and sunscreen, plus a compact umbrella or rain jacket. See the full September packing list for St. Louis for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.