ERA5 almanac comparison — 8 years of real data
Bar Harbor vs Hilton Head: weather in September
Hilton Head edges out Bar Harbor for sun in September: 33% clear historically versus 16% (8-year ERA5 average, a 17-point gap). Hilton Head also sees measurably more rain than Bar Harbor this month (50% vs 27% of days). Both are viable — Hilton Head 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.
Bar Harbor
ME
- Clear days, September
- 16%
- Sample size
- n=240 days
- Avg high
- 68°F
- Early September (1st–15th)
- 22%
- Late September (16th–end)
- 9%
- Rain frequency
- 27% of days
Hilton Head
SC
- Clear days, September
- 33%
- Sample size
- n=240 days
- Avg high
- 83°F
- Early September (1st–15th)
- 28%
- Late September (16th–end)
- 38%
- Rain frequency
- 50% of days
Compare Bar Harbor vs Hilton Head 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.