ERA5 almanac comparison — 8 years of real data
Austin vs Puerto Rico: weather in September
Austin is the clear winner for sun in September: 41% of days historically clear versus just 4% in Puerto Rico — a 37-point gap across 8 years of ERA5 data. Puerto Rico also sees measurably more rain than Austin this month (74% vs 34% of days). This isn't close.
Austin
TX
- Clear days, September
- 41%
- Sample size
- n=240 days
- Avg high
- 91°F
- Early September (1st–15th)
- 35%
- Late September (16th–end)
- 47%
- Rain frequency
- 34% of days
Puerto Rico
PR
- Clear days, September
- 4%
- Sample size
- n=240 days
- Avg high
- 87°F
- Early September (1st–15th)
- 4%
- Late September (16th–end)
- 5%
- Rain frequency
- 74% of days
Frequently asked
Is Austin or Puerto Rico warmer in September?
Austin runs warmer by day in September. Austin averages highs of 91°F (highs n=240 days); Puerto Rico averages highs of 87°F (highs n=240 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Austin or Puerto Rico in September?
Puerto Rico is measurably wetter than Austin. Days with measurable rain: Austin 34%, Puerto Rico 74% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Austin or Puerto Rico?
Austin is the clear winner for sun in September: 41% of days historically clear versus just 4% in Puerto Rico — a 37-point gap across 8 years of ERA5 data. Puerto Rico also sees measurably more rain than Austin this month (74% vs 34% of days). This isn't close.
Compare Austin vs Puerto Rico 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.