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SunnyDays

ERA5 almanac — 8 years of real data

Sea Island in April

Sea Island in April is historically a poor month for sun: only 36% of days clear across 8 years (n=240, avg high 74°F). Historical average, not a forecast.

What you are reading: 8-year historical averages from the ERA5 reanalysis, not a forecast. A month that is historically 90% clear can still be overcast on your specific trip. For this week’s actual forecast, see the live Sea Island page. Both can be true at once: “historically strong in this month; this particular week is not.” We label which is which.

Early vs. Late April

Clear-sky percentage for Sea Island in April, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early April
1st–15th		 24% n=120 74°F
Late April
16th–end		 49% n=120 74°F
Full month average 36% n=240 74°F

Bottom line

Sea Island is mostly overcast in April historically: only 36% of days are clear across 8 years (n=240), avg high 74°F. The two halves differ materially (24% early, 49% late) — favour the late half of the month. Most visitors this month will see more clouds than sun.

Every month in Sea Island

Compare across all months with data. Numbers are historical clear-sky %.

Historical clear-sky % for Sea Island, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 2% n=248 All destinations →
February 8% n=226 All destinations →
March 15% n=248 All destinations →
April ← this page 36% n=240 All destinations →
May 36% n=248 All destinations →
June 24% n=240 All destinations →
July 14% n=248 All destinations →
August 7% n=248 All destinations →
September 32% n=240 All destinations →
October 42% n=248 All destinations →
November 17% n=240 All destinations →
December 7% n=248 All destinations →

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.