ERA5 almanac comparison — 8 years of real data
Birmingham vs San Diego: weather in May
Birmingham edges out San Diego for sun in May: 36% clear historically versus 13% (8-year ERA5 average, a 23-point gap). Both are viable — Birmingham is the safer bet.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific May. For this
week’s actual forecast, each destination links to its live page below.
Birmingham
AL
- Clear days, May
- 36%
- Sample size
- n=248 days
- Avg high
- 81°F
- Early May (1st–15th)
- 33%
- Late May (16th–end)
- 39%
San Diego
CA
- Clear days, May
- 13%
- Sample size
- n=248 days
- Avg high
- 68°F
- Early May (1st–15th)
- 16%
- Late May (16th–end)
- 10%
- Rain frequency
- 10% of days
Compare Birmingham vs San Diego in another month
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.