ERA5 almanac comparison — 8 years of real data
Key West vs Miami: weather in September
Key West edges out Miami for sun in September: 11% clear historically versus 4% (8-year ERA5 average, a 7-point gap). Miami also sees measurably more rain than Key West this month (80% vs 64% of days). Both are viable — Key West is the safer bet.
Key West
FL
- Clear days, September
- 11%
- Sample size
- n=240 days
- Avg high
- 85°F
- Early September (1st–15th)
- 14%
- Late September (16th–end)
- 8%
- Rain frequency
- 64% of days
Miami
FL
- Clear days, September
- 4%
- Sample size
- n=240 days
- Avg high
- 86°F
- Early September (1st–15th)
- 5%
- Late September (16th–end)
- 4%
- Rain frequency
- 80% of days
Frequently asked
Is Key West or Miami warmer in September?
Miami runs warmer by day in September. Key West averages highs of 85°F (highs n=240 days); Miami averages highs of 86°F (highs n=240 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Key West or Miami in September?
Miami is measurably wetter than Key West. Days with measurable rain: Key West 64%, Miami 80% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Key West or Miami?
Key West edges out Miami for sun in September: 11% clear historically versus 4% (8-year ERA5 average, a 7-point gap). Miami also sees measurably more rain than Key West this month (80% vs 64% of days). Both are viable — Key West is the safer bet.
Compare Key West vs Miami in another month
All percentages are historical averages from the ERA5 reanalysis via Open-Meteo, 8 full years (2018–2025). “Clear” means avg high ≥ 72 °F, precipitation < 1 mm, and a non-precipitation weather code. This is history, not a forecast. The live forecast for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.