ERA5 almanac comparison — 8 years of real data
Cancún vs San Antonio: weather in December
Essentially a tie in December: Cancún is 20% clear historically, San Antonio is 17% clear (8-year ERA5 average) — within the noise. Avg high 80°F vs 68°F. Cancún also sees measurably more rain than San Antonio this month (47% vs 21% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.
Cancún
Mexico
- Clear days, December
- 20%
- Sample size
- n=248 days
- Avg high
- 80°F
- Early December (1st–15th)
- 22%
- Late December (16th–end)
- 18%
- Rain frequency
- 47% 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
Frequently asked
Is Cancún or San Antonio warmer in December?
Cancún runs warmer by day in December. Cancún averages highs of 80°F (highs n=248 days); San Antonio averages highs of 68°F (highs n=248 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Cancún or San Antonio in December?
Cancún is measurably wetter than San Antonio. Days with measurable rain: Cancún 47%, San Antonio 21% (n=248 and n=248 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in December, Cancún or San Antonio?
Essentially a tie in December: Cancún is 20% clear historically, San Antonio is 17% clear (8-year ERA5 average) — within the noise. Avg high 80°F vs 68°F. Cancún also sees measurably more rain than San Antonio this month (47% vs 21% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.
Compare Cancún 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 forecast for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.