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SunnyDays

ERA5 almanac — 8 years of real data

Birmingham in May

Birmingham in May: 38% of days see measurable rain, 81°F average high, 36% of days historically clear (n=248, ERA5 2018–2025).

Birmingham in May is historically a poor month for sun: only 36% of days clear across 8 years (n=248, avg high 81°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 Birmingham 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 Birmingham 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		 33% n=120 81°F
Late May
16th–end		 39% n=128 81°F
Full month average 36% 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 Birmingham 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		 78% n=120
Late May
16th–end		 90% n=128
Full month average 84% n=248
12.1 h median sunshine per day 83% 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: 36%. Sunshine-based “warm & sunny”: 84%. The 48-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

Birmingham is mostly overcast in May historically: only 36% of days are clear across 8 years (n=248), avg high 81°F. Most visitors this month will see more clouds than sun.

Every month in Birmingham

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

Historical clear-sky % for Birmingham, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 1% n=226 All destinations →
March 9% n=248 All destinations →
April 27% n=240 All destinations →
May ← this page 36% n=248 All destinations →
June 30% n=240 All destinations →
July 17% n=248 All destinations →
August 28% n=248 All destinations →
September 49% n=240 All destinations →
October 44% n=248 All destinations →
November 14% n=240 All destinations →
December 1% n=248 All destinations →

Frequently asked

Does it rain in Birmingham in May?

Sometimes. Birmingham 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 Birmingham good for sun in May?

It's mixed. Birmingham in May is clear on 36% of days historically (avg high 81°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Birmingham compares in May

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Birmingham 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.