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SunnyDays

ERA5 almanac comparison — 8 years of real data

Sea Island vs St. Martin: weather in July

Essentially a tie in July: Sea Island is 14% clear historically, St. Martin is 11% clear (8-year ERA5 average) — within the noise. Avg high 87°F vs 80°F. Sea Island also sees measurably more rain than St. Martin this month (64% vs 49% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.

What you are reading: 8-year historical averages, not a forecast. Either destination can still surprise you this specific July. For this week’s actual forecast, each destination links to its live page below.

Sea Island

GA

Clear days, July
14%
Sample size
n=248 days
Avg high
87°F
Early July (1st–15th)
12%
Late July (16th–end)
16%
Rain frequency
64% of days
See this week’s live forecast →

St. Martin

SX

Clear days, July
11%
Sample size
n=248 days
Avg high
80°F
Early July (1st–15th)
15%
Late July (16th–end)
7%
Rain frequency
49% of days

Compare Sea Island vs St. Martin 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.