ERA5 almanac comparison — 8 years of real data
Dallas vs Sea Island: weather in September
Dallas edges out Sea Island for sun in September: 48% clear historically versus 32% (8-year ERA5 average, a 16-point gap). Sea Island also sees measurably more rain than Dallas this month (53% vs 30% of days). Both are viable — Dallas is the safer bet.
Dallas
TX
- Clear days, September
- 48%
- Sample size
- n=240 days
- Avg high
- 90°F
- Early September (1st–15th)
- 46%
- Late September (16th–end)
- 51%
- Rain frequency
- 30% of days
Sea Island
GA
- Clear days, September
- 32%
- Sample size
- n=240 days
- Avg high
- 83°F
- Early September (1st–15th)
- 26%
- Late September (16th–end)
- 37%
- Rain frequency
- 53% of days
Frequently asked
Is Dallas or Sea Island warmer in September?
Dallas runs warmer by day in September. Dallas averages highs of 90°F (highs n=240 days); Sea Island averages highs of 83°F (highs n=240 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Dallas or Sea Island in September?
Sea Island is measurably wetter than Dallas. Days with measurable rain: Dallas 30%, Sea Island 53% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Dallas or Sea Island?
Dallas edges out Sea Island for sun in September: 48% clear historically versus 32% (8-year ERA5 average, a 16-point gap). Sea Island also sees measurably more rain than Dallas this month (53% vs 30% of days). Both are viable — Dallas is the safer bet.
Compare Dallas vs Sea 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.