ERA5 almanac comparison — 8 years of real data
Hilton Head vs Hudson Valley: weather in September
Essentially a tie in September: Hilton Head is 33% clear historically, Hudson Valley is 33% clear (8-year ERA5 average) — within the noise. Avg high 83°F vs 75°F. Hilton Head also sees measurably more rain than Hudson Valley this month (50% vs 31% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.
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
Hudson Valley
NY
- Clear days, September
- 33%
- Sample size
- n=240 days
- Avg high
- 75°F
- Early September (1st–15th)
- 38%
- Late September (16th–end)
- 28%
- Rain frequency
- 31% of days
Compare Hilton Head vs Hudson Valley 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.