ERA5 almanac comparison — 8 years of real data
Charlotte vs Vail: weather in September
Charlotte edges out Vail for sun in September: 44% clear historically versus 23% (8-year ERA5 average, a 21-point gap). Both are viable — Charlotte is the safer bet.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific September. For this
week’s actual forecast, each destination links to its live page below.
Charlotte
NC
- Clear days, September
- 44%
- Sample size
- n=240 days
- Avg high
- 82°F
- Early September (1st–15th)
- 47%
- Late September (16th–end)
- 41%
- Rain frequency
- 31% of days
Vail
CO
- Clear days, September
- 23%
- Sample size
- n=240 days
- Avg high
- 70°F
- Early September (1st–15th)
- 38%
- Late September (16th–end)
- 8%
- Rain frequency
- 22% of days
Compare Charlotte vs Vail 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 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.