ERA5 almanac comparison — 8 years of real data
Austin vs Puerto Rico: weather in December
Essentially a tie in December: Austin is 11% clear historically, Puerto Rico is 14% clear (8-year ERA5 average) — within the noise. Avg high 66°F vs 83°F. Puerto Rico also sees measurably more rain than Austin this month (55% vs 25% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.
Austin
TX
- Clear days, December
- 11%
- Sample size
- n=248 days
- Avg high
- 66°F
- Early December (1st–15th)
- 13%
- Late December (16th–end)
- 9%
- Rain frequency
- 25% of days
Puerto Rico
PR
- Clear days, December
- 14%
- Sample size
- n=248 days
- Avg high
- 83°F
- Early December (1st–15th)
- 12%
- Late December (16th–end)
- 16%
- Rain frequency
- 55% of days
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 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.