ERA5 almanac comparison — 8 years of real data
Martha's Vineyard vs Sea Island: weather in January
Essentially a tie in January: Martha's Vineyard is 0% clear historically, Sea Island is 2% clear (8-year ERA5 average) — within the noise. Avg high 40°F vs 60°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Martha's Vineyard
MA
- Clear days, January
- 0%
- Sample size
- n=248 days
- Avg high
- 40°F
- Early January (1st–15th)
- 0%
- Late January (16th–end)
- 0%
- Rain frequency
- 34% of days
Sea Island
GA
- Clear days, January
- 2%
- Sample size
- n=248 days
- Avg high
- 60°F
- Early January (1st–15th)
- 3%
- Late January (16th–end)
- 2%
- Rain frequency
- 24% of days
Frequently asked
Is Martha's Vineyard or Sea Island warmer in January?
Sea Island runs warmer by day in January. Martha's Vineyard averages highs of 40°F (highs n=248 days); Sea Island averages highs of 60°F (highs n=248 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Martha's Vineyard or Sea Island in January?
Days with measurable rain: Martha's Vineyard 34%, Sea Island 24% (n=248 and n=248 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in January, Martha's Vineyard or Sea Island?
Essentially a tie in January: Martha's Vineyard is 0% clear historically, Sea Island is 2% clear (8-year ERA5 average) — within the noise. Avg high 40°F vs 60°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Compare Martha's Vineyard 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.