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SunnyDays

ERA5 almanac — 8 years of real data

30A / Seaside in May

30A / Seaside in May: 38% of days see measurable rain, 81°F average high, 42% of days historically clear (n=248, ERA5 2018–2025).

30A / Seaside in May is a mixed month for sun: 42% of days historically clear (n=248, avg high 81°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 30A / Seaside 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 30A / Seaside 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		 51% n=120 81°F
Late May
16th–end		 34% n=128 81°F
Full month average 42% n=248 81°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 30A / Seaside 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		 94% n=120
Late May
16th–end		 93% n=128
Full month average 93% n=248
12.8 h median sunshine per day 90% of days exceed 8 h sunshine 38% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 42%. Sunshine-based “warm & sunny”: 93%. The 51-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

30A / Seaside in May is genuinely mixed: 42% of days historically clear (n=248), avg high 81°F — more cloudy than clear. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in 30A / Seaside

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

Historical clear-sky % for 30A / Seaside, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 1% n=248 All destinations →
February 5% n=226 All destinations →
March 12% n=248 All destinations →
April 41% n=240 All destinations →
May ← this page 42% n=248 All destinations →
June 16% n=240 All destinations →
July 9% n=248 All destinations →
August 12% n=248 All destinations →
September 32% n=240 All destinations →
October 51% n=248 All destinations →
November 24% n=240 All destinations →
December 4% n=248 All destinations →

Frequently asked

Does it rain in 30A / Seaside in May?

Sometimes. 30A / Seaside sees measurable rain on 38% of days in May historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is 30A / Seaside good for sun in May?

It's mixed. 30A / Seaside in May is clear on 42% of days historically (avg high 81°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How 30A / Seaside compares in May

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against 30A / Seaside 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.