ERA5 almanac comparison — 8 years of real data
Puerto Vallarta vs Tucson: weather in September
Tucson is the clear winner for sun in September: 70% of days historically clear versus just 4% in Puerto Vallarta — a 66-point gap across 8 years of ERA5 data. Puerto Vallarta also sees measurably more rain than Tucson this month (78% vs 20% of days). This isn't close.
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.
Puerto Vallarta
MX
- Clear days, September
- 4%
- Sample size
- n=240 days
- Avg high
- 86°F
- Early September (1st–15th)
- 3%
- Late September (16th–end)
- 4%
- Rain frequency
- 78% of days
Tucson
AZ
- Clear days, September
- 70%
- Sample size
- n=240 days
- Avg high
- 96°F
- Early September (1st–15th)
- 72%
- Late September (16th–end)
- 69%
- Rain frequency
- 20% of days
Compare Puerto Vallarta vs Tucson 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.