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SunnyDays

ERA5 almanac — 8 years of real data

St. Augustine in May

St. Augustine in May is a mixed month for sun: 40% of days historically clear (n=248, avg high 82°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 St. Augustine 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 St. Augustine 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		 42% n=120 82°F
Late May
16th–end		 39% n=128 82°F
Full month average 40% n=248 82°F

Sunshine & warmth in May

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 St. Augustine in May. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early May
1st–15th		 92% n=120
Late May
16th–end		 92% n=128
Full month average 92% n=248
12.9 h median sunshine per day 89% of days exceed 8 h sunshine 33% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 40%. Sunshine-based “warm & sunny”: 92%. The 52-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

St. Augustine in May is genuinely mixed: 40% of days historically clear (n=248), avg high 82°F — more cloudy than clear. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in St. Augustine

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

Historical clear-sky % for St. Augustine, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 9% n=248 All destinations →
February 22% n=226 All destinations →
March 25% n=248 All destinations →
April 42% n=240 All destinations →
May ← this page 40% n=248 All destinations →
June 14% n=240 All destinations →
July 9% n=248 All destinations →
August 6% n=248 All destinations →
September 17% n=240 All destinations →
October 34% n=248 All destinations →
November 23% n=240 All destinations →
December 13% 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.