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SunnyDays

ERA5 almanac — 8 years of real data

Sea Island in April

Sea Island in April: 28% of days see measurable rain, 74°F average high, 36% of days historically clear (n=240, ERA5 2018–2025).

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

Sunshine & warmth in April

A second measure using actual sunshine hours (ERA5 sunshine_duration), not the daily weather code. A Lowcountry day with 12 hours of sun and a 25-minute afternoon storm is counted below as a warm, sunny day — because it was. How we define this.

Sunshine-based metrics for Sea Island in April. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early April
1st–15th		 52% n=120
Late April
16th–end		 82% n=120
Full month average 67% n=240
12.3 h median sunshine per day 86% of days exceed 8 h sunshine 28% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 36%. Sunshine-based “warm & sunny”: 67%. The 31-point gap is from brief afternoon convective storms that stamp the whole day as “rain” in the WMO code but leave the bulk of the sunshine untouched.

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 →

Frequently asked

Does it rain in Sea Island in April?

Sometimes. Sea Island sees measurable rain on 28% of days in April historically (n=240 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Sea Island good for sun in April?

It's mixed. Sea Island in April is clear on 36% of days historically (avg high 74°F, n=240 days, ERA5 2018–2025) — the outcome varies year to year.

How Sea Island compares in April

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Sea Island this month — same passport tier, similar flight distance, both sides from the same 8-year ERA5 record.

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.