ERA5 almanac comparison — 8 years of real data
Charleston vs Kiawah Island: weather in September
Essentially a tie in September: Charleston is 32% clear historically, Kiawah Island is 33% clear (8-year ERA5 average) — within the noise. Avg high 83°F vs 83°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Charleston
SC
- Clear days, September
- 32%
- Sample size
- n=240 days
- Avg high
- 83°F
- Early September (1st–15th)
- 28%
- Late September (16th–end)
- 37%
- Rain frequency
- 46% of days
Kiawah Island
SC
- Clear days, September
- 33%
- Sample size
- n=240 days
- Avg high
- 83°F
- Early September (1st–15th)
- 29%
- Late September (16th–end)
- 37%
- Rain frequency
- 44% of days
Frequently asked
Is Charleston or Kiawah Island warmer in September?
Equally warm by day in September. Charleston averages highs of 83°F (highs n=240 days); Kiawah Island averages highs of 83°F (highs n=240 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Charleston or Kiawah Island in September?
Days with measurable rain: Charleston 46%, Kiawah Island 44% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Charleston or Kiawah Island?
Essentially a tie in September: Charleston is 32% clear historically, Kiawah Island is 33% clear (8-year ERA5 average) — within the noise. Avg high 83°F vs 83°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Compare Charleston vs Kiawah Island 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.