ERA5 almanac comparison — 8 years of real data
Jamaica vs San Antonio: weather in December
Essentially a tie in December: Jamaica is 21% clear historically, San Antonio is 17% clear (8-year ERA5 average) — within the noise. Avg high 82°F vs 68°F. Jamaica also sees measurably more rain than San Antonio this month (45% vs 21% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.
Jamaica
JM
- Clear days, December
- 21%
- Sample size
- n=248 days
- Avg high
- 82°F
- Early December (1st–15th)
- 17%
- Late December (16th–end)
- 24%
- Rain frequency
- 45% of days
San Antonio
TX
- Clear days, December
- 17%
- Sample size
- n=248 days
- Avg high
- 68°F
- Early December (1st–15th)
- 20%
- Late December (16th–end)
- 14%
- Rain frequency
- 21% of days
Compare Jamaica vs San Antonio 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.