ERA5 almanac — 8 years of real data

Atlanta in May

Atlanta in May: 43% of days see measurable rain, 80°F average high, 32% of days historically clear (n=248, ERA5 2018–2025).

Atlanta in May is historically a poor month for sun: only 32% 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 Atlanta 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 Atlanta 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	26%	n=120	80°F
Late May 16th–end	37%	n=128	80°F
Full month average	32%	n=248	80°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 Atlanta 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	71%	n=120
Late May 16th–end	87%	n=128
Full month average	79%	n=248

12.0 h median sunshine per day 79% of days exceed 8 h sunshine 43% of days see ≥ 1 mm rain — rain is not hidden

Comparison (old vs new): WMO-code “clear” bar: 32%. Sunshine-based “warm & sunny”: 79%. The 47-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

Atlanta is mostly overcast in May historically: only 32% 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 Atlanta

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

Historical clear-sky % for Atlanta, all months, ERA5 2018–2025.
Month	% Clear	Sample (n)
January	0%	n=248	All destinations →
February	2%	n=226	All destinations →
March	11%	n=248	All destinations →
April	24%	n=240	All destinations →
May ← this page	32%	n=248	All destinations →
June	26%	n=240	All destinations →
July	15%	n=248	All destinations →
August	20%	n=248	All destinations →
September	40%	n=240	All destinations →
October	34%	n=248	All destinations →
November	6%	n=240	All destinations →
December	1%	n=248	All destinations →

Frequently asked

Does it rain in Atlanta in May?

Sometimes. Atlanta sees measurable rain on 43% of days in May historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Atlanta good for sun in May?

It's mixed. Atlanta in May is clear on 32% of days historically (avg high 80°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Atlanta compares in May

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Atlanta this month — same passport tier, similar flight distance, both sides from the same 8-year ERA5 record.

→ Atlanta vs Charlottesville in May — Charlottesville is 32% clear historically
→ Atlanta vs Memphis in May — Memphis is 32% clear historically
→ Atlanta vs Denver in May — Denver is 33% clear historically

→ Atlanta live forecast — this week’s actual 7-day weather, not historical
→ Best destinations in May — all destinations ranked by May clear-sky %
→ All destinations
→ Raw data (JSON) — buckets, n, source

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.