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SunnyDays

ERA5 almanac — 8 years of real data

Kiawah Island in August

Kiawah Island in August is historically a poor month for sun: only 10% of days clear across 8 years (n=248, avg high 85°F). October is the clearest month for Kiawah Island historically. 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 August

Clear-sky percentage for Kiawah Island in August, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early August
1st–15th		 8% n=120 85°F
Late August
16th–end		 12% n=128 85°F
Full month average 10% n=248 85°F

Sunshine & warmth in August

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 August. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early August
1st–15th		 88% n=120
Late August
16th–end		 91% n=128
Full month average 90% n=248
12.0 h median sunshine per day 84% of days exceed 8 h sunshine 64% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 10%. Sunshine-based “warm & sunny”: 90%. The 80-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 is a poor choice for sun in August: just 10% of days clear historically (n=248). October is the historically strongest month for sun here. The 8-year record is consistent — this is not a fluke bad stretch.

→ See all destinations in October — historically the best month for sun in Kiawah Island.

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 38% n=248 All destinations →
June 22% n=240 All destinations →
July 7% n=248 All destinations →
August ← this page 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.