ERA5 almanac comparison — 8 years of real data
Portland vs San Antonio: weather in August
San Antonio edges out Portland for sun in August: 45% clear historically versus 39% (8-year ERA5 average, a 6-point gap). Both are viable — San Antonio is the safer bet.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific August. For this
week’s actual forecast, each destination links to its live page below.
Portland
ME
- Clear days, August
- 39%
- Sample size
- n=248 days
- Avg high
- 78°F
- Early August (1st–15th)
- 41%
- Late August (16th–end)
- 37%
San Antonio
TX
- Clear days, August
- 45%
- Sample size
- n=248 days
- Avg high
- 97°F
- Early August (1st–15th)
- 51%
- Late August (16th–end)
- 39%
- Rain frequency
- 24% of days
Compare Portland vs San Antonio 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.