ERA5 almanac comparison — 8 years of real data
Cancún vs Kiawah Island: weather in September
Kiawah Island edges out Cancún for sun in September: 33% clear historically versus 5% (8-year ERA5 average, a 28-point gap). Cancún also sees measurably more rain than Kiawah Island this month (71% vs 44% of days). Both are viable — Kiawah Island is the safer bet.
Cancún
Mexico
- Clear days, September
- 5%
- Sample size
- n=240 days
- Avg high
- 88°F
- Early September (1st–15th)
- 5%
- Late September (16th–end)
- 5%
- Rain frequency
- 71% 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 Cancún or Kiawah Island warmer in September?
Cancún runs warmer by day in September. Cancún averages highs of 88°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 Cancún or Kiawah Island in September?
Cancún is measurably wetter than Kiawah Island. Days with measurable rain: Cancún 71%, Kiawah Island 44% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Cancún or Kiawah Island?
Kiawah Island edges out Cancún for sun in September: 33% clear historically versus 5% (8-year ERA5 average, a 28-point gap). Cancún also sees measurably more rain than Kiawah Island this month (71% vs 44% of days). Both are viable — Kiawah Island is the safer bet.
Compare Cancún 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.