Key West in September
In September, Key West averages 29°C (84°F) during the day and 27°C (81°F) at night, with frequent rain — about 26 days of the month see precipitation (159 mm total).
Off-peakConditions are warm and beach-friendly. Expect daily rain or showers, often in heavy bursts.
It's peak hurricane season in Key West 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 Key West
September is one of the warmest months in Key West (3rd of 12) and one of the wettest months (1st of 12). Daytime temperature runs 3°C above the annual average (26°C). September runs 1°C cooler than August (30°C) and cools 1°C in October (28°C).
September sunrise & sunset in Key West
Times shown for Key West local time (America/New_York), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in Key West — September
Golden-hour and blue-hour windows for the 15th of September, in Key West's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Key West 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 (Off-peak) and Key West's popularity.
Crowds & pricing — September in Key West
This is off-peak for Key West — the lowest prices of the year and the fewest crowds, but with real trade-offs: some restaurants, hotels, and beach businesses may close for the season; weather conditions can make outdoor activities unpredictable; and a handful of seasonal sights run reduced hours or close entirely. Great if you prefer a quiet local rhythm and don't mind the climate giving you reasons to choose indoor activities.
Why this tier: peak hazard season (1 active)
Sun & mosquito risk — September in Key West
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.
Sea temperature in Key West — September
Across the year Key West's sea swings from 24.2°C (January) to 31.4°C (August) — September sits at 31°C.
Key West in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 23°C / 73°F | 20°C / 69°F | 52 mm | 16 | — |
| February | 24°C / 74°F | 22°C / 71°F | 30 mm | 13 | — |
| March | 24°C / 76°F | 23°C / 73°F | 34 mm | 14 | — |
| April | 26°C / 78°F | 24°C / 76°F | 40 mm | 15 | — |
| May | 27°C / 81°F | 25°C / 78°F | 93 mm | 18 | — |
| June | 29°C / 83°F | 27°C / 80°F | 116 mm | 24 | — |
| July | 30°C / 85°F | 28°C / 82°F | 91 mm | 23 | — |
| August | 30°C / 85°F | 28°C / 82°F | 109 mm | 25 | — |
| September | 29°C / 84°F | 27°C / 81°F | 159 mm | 26 | — |
| October | 28°C / 82°F | 26°C / 79°F | 132 mm | 25 | — |
| November | 26°C / 78°F | 24°C / 75°F | 76 mm | 19 | — |
| December | 24°C / 76°F | 22°C / 72°F | 56 mm | 14 | — |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Key West in September →
Frequently asked questions
How hot is Key West in September?
In September, Key West averages a high of 29°C (84°F) and a low of 27°C (81°F) — generally warm.
Does it rain a lot in Key West in September?
September is quite rainy in Key West, with about 26 rainy days on average.
Is September a good time to visit Key West?
September is warm but on the rainy side. 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 Key West in September?
Pack lightweight, breathable clothing, sunglasses and sunscreen, plus a compact umbrella or rain jacket. See the full September packing list for Key West for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.