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SunnyDays

ERA5 almanac — 8 years of real data

Kiawah Island in April

Kiawah Island in April is a mixed month for sun: 41% of days historically clear (n=240, avg high 74°F). The outcome varies year to year — check the early/late split below. 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 Kiawah 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 Kiawah 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		 35% n=120 74°F
Late April
16th–end		 47% n=120 74°F
Full month average 41% 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 Kiawah 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		 62% n=120
Late April
16th–end		 75% n=120
Full month average 68% n=240
12.3 h median sunshine per day 88% of days exceed 8 h sunshine 26% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 41%. Sunshine-based “warm & sunny”: 68%. The 27-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

Kiawah Island in April is genuinely mixed: 41% of days historically clear (n=240), avg high 74°F — more cloudy than clear. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Kiawah Island

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

Historical clear-sky % for Kiawah Island, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 1% n=248 All destinations →
February 6% n=226 All destinations →
March 14% n=248 All destinations →
April ← this page 41% n=240 All destinations →
May 38% n=248 All destinations →
June 22% n=240 All destinations →
July 7% n=248 All destinations →
August 10% n=248 All destinations →
September 33% n=240 All destinations →
October 46% n=248 All destinations →
November 14% n=240 All destinations →
December 4% 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.