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SunnyDays

ERA5 almanac — 8 years of real data

Kiawah Island in May

Kiawah Island in May is historically a poor month for sun: only 38% of days clear across 8 years (n=248, avg high 80°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 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 May

Clear-sky percentage for Kiawah Island in May, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early May
1st–15th		 45% n=120 80°F
Late May
16th–end		 32% n=128 80°F
Full month average 38% n=248 80°F

Bottom line

Kiawah Island is mostly overcast in May historically: only 38% of days are clear across 8 years (n=248), avg high 80°F. Most visitors this month will see more clouds than 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 41% n=240 All destinations →
May ← this page 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.