September 18 is generally a great time to visit Key West. While there is a slight chance of rain (37%), showers are usually brief. Expect comfortable 29°C weather. It's a lively time to explore Key West, with most attractions operating at full capacity.
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Essential Travel Info for Key West
Currency
USD
$ United States dollar
Language
English
Driving
Right side
Safety
Moderate Safety
GPI: 2.44
Key West Weather Forecast for September 18
"Warm & Sunny. Expect average highs of 29°C. 37% chance of rain."
What to Wear in Key West in September
Based on historical data for September 18, Key West typically experiences temperatures between 26.9°C and 29°C. We recommend packing t-shirt, light clothing, umbrella to stay comfortable. With a 37% chance of rain, keeping a raincoat or umbrella handy is a smart move.
Complete Packing Guide
Weekly breakdown & essential items for Key West
Smart Suitcase
- T-Shirt
- Light Clothing
- Umbrella
Average High
29°C
Daytime Peak
Average Low
26.9°C
Nighttime Low
Feels Like
34.3°C
🔥 Heat index effect
Rain Chance
37%
Avg 2.7mm if it rains
Cloud Cover
57%
Light drizzle
Pressure
1013.8 hPa
Low volatility
Key West Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
🎯 This date historically delivers consistent weather 82% of the time. Safe to plan outdoor activities with confidence.
Sun Exposure
UV Index & Safety Guide
Protection Needed
SPF 30 recommended
06:00 - 10:00
16:00 - 18:00
Type I-II
🔴 24 min to burn
Type III-IV
🟡 36 min to burn
Type V-VI
🟢 60 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
24.8°C
Humid/Sticky
Heat Index
34.3°C
Feels hotter
😕 Best outdoor time:
Morning hours (before 11 AM)
Marine Conditions
Jellyfish Warning
High water temps may attract jellyfish swarms.
Swim Index
✅ Excellent Swimming Conditions
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in United States
Flight Traffic
Busy
64/100 pressure index
Health Advisory
Healthy
Routine only • View Details →
Landing Slots
~25
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Key West
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:15
☀️ Noon
12:22
🌇 Sunset
18:29
⏱️ Daylight
12h 14m
Wind Speed
21.6 km/h
Moderate wind
Sunshine
10.1 hrs
Direct Sun (Cloud-free)
Humidity
78%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Key West
Smart Flight Estimator
Airport-to-Airport Logistics
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Travel Health & Safety in Key West
Travel Comfort Index
Real-time tourism conditions
Weather Quality
⛅ Good
Tourist Crowds
🟡 Busy
Price Level
💰💰💰 Expensive
Health & Wellbeing
Meteo-Health Forecast
Stable conditions. Low risk of headaches.
Weather unlikely to affect joint pain.
Moderate fish activity expected.
Air quality is excellent. Perfect for outdoor activities.
Regional Safety Profile
Seismic Activity
Zero seismic activity detected in 30 years.
Atlantic Hurricane Risk
Season: Jun - Nov
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Key West on September 18 averages 29°C with a 37% precipitation probability. Wedding/Outdoor Event Score: 87/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Key West Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Compare Other Cities
Same date (September 18) in other destinations
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📍 Is Key West Worth Visiting on September 18?
Planning a trip to Key West on September 18? Our historical weather analysis based on 30 years of NASA satellite data shows that this time of year typically offers vibrant summer conditions averaging 29°C with a 37% historical precipitation risk.
✈️ Travel Logistics: Approximately 25 landing slots available daily during this period, indicating manageable crowd levels.
🌊 Coastal Conditions: Water temperature averages 31.4°C (hot soup). Wave conditions are generally lake-like with heights around 0.42m.
📊 Historical Extremes: The hottest September 18 recorded in the last 30 years saw temperatures hit 30.3°C in 2023, while the coldest dropped to 26°C in 2022.