ERA5 almanac comparison — 8 years of real data
Birmingham vs Charleston: weather in September
Birmingham edges out Charleston for sun in September: 49% clear historically versus 32% (8-year ERA5 average, a 17-point gap). Charleston also sees measurably more rain than Birmingham this month (46% vs 31% of days). Both are viable — Birmingham is the safer bet.
Birmingham
AL
- Clear days, September
- 49%
- Sample size
- n=240 days
- Avg high
- 86°F
- Early September (1st–15th)
- 44%
- Late September (16th–end)
- 54%
- Rain frequency
- 31% of days
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
Frequently asked
Is Birmingham or Charleston warmer in September?
Birmingham runs warmer by day in September. Birmingham averages highs of 86°F (highs n=240 days); Charleston averages highs of 83°F (highs n=240 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Birmingham or Charleston in September?
Charleston is measurably wetter than Birmingham. Days with measurable rain: Birmingham 31%, Charleston 46% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Birmingham or Charleston?
Birmingham edges out Charleston for sun in September: 49% clear historically versus 32% (8-year ERA5 average, a 17-point gap). Charleston also sees measurably more rain than Birmingham this month (46% vs 31% of days). Both are viable — Birmingham is the safer bet.
Compare Birmingham vs Charleston 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.