ERA5 almanac comparison — 8 years of real data
Park City vs Portland: weather in September
Essentially a tie in September: Park City is 30% clear historically, Portland is 30% clear (8-year ERA5 average) — within the noise. Avg high 70°F vs 71°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Park City
UT
- Clear days, September
- 30%
- Sample size
- n=240 days
- Avg high
- 70°F
- Early September (1st–15th)
- 41%
- Late September (16th–end)
- 19%
- Rain frequency
- 32% of days
Portland
ME
- Clear days, September
- 30%
- Sample size
- n=240 days
- Avg high
- 71°F
- Early September (1st–15th)
- 40%
- Late September (16th–end)
- 19%
- Rain frequency
- 28% of days
Frequently asked
Is Park City or Portland warmer in September?
Portland runs warmer by day in September. Park City averages highs of 70°F (highs n=240 days); Portland averages highs of 71°F (highs n=240 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Park City or Portland in September?
Days with measurable rain: Park City 32%, Portland 28% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Park City or Portland?
Essentially a tie in September: Park City is 30% clear historically, Portland is 30% clear (8-year ERA5 average) — within the noise. Avg high 70°F vs 71°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Compare Park City vs Portland 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 forecast for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.