ERA5 almanac comparison — 8 years of real data
Big Sur vs Crater Lake: weather in September
Big Sur edges out Crater Lake for sun in September: 35% clear historically versus 24% (8-year ERA5 average, a 11-point gap). Both are viable — Big Sur is the safer bet.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific September. For this
week’s actual forecast, each destination links to its live page below.
Big Sur
CA
- Clear days, September
- 35%
- Sample size
- n=240 days
- Avg high
- 72°F
- Early September (1st–15th)
- 40%
- Late September (16th–end)
- 30%
- Rain frequency
- 4% of days
Crater Lake
OR
- Clear days, September
- 24%
- Sample size
- n=240 days
- Avg high
- 66°F
- Early September (1st–15th)
- 37%
- Late September (16th–end)
- 11%
Compare Big Sur vs Crater Lake 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.