ERA5 almanac comparison — 8 years of real data
Mérida vs Mexico City: weather in December
Essentially a tie in December: Mérida is 53% clear historically, Mexico City is 50% clear (8-year ERA5 average) — within the noise. Avg high 84°F vs 72°F. Mérida also sees measurably more rain than Mexico City this month (21% vs 6% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.
Mérida
MX
- Clear days, December
- 53%
- Sample size
- n=248 days
- Avg high
- 84°F
- Early December (1st–15th)
- 58%
- Late December (16th–end)
- 48%
- Rain frequency
- 21% of days
Mexico City
MX
- Clear days, December
- 50%
- Sample size
- n=248 days
- Avg high
- 72°F
- Early December (1st–15th)
- 60%
- Late December (16th–end)
- 40%
- Rain frequency
- 6% of days
Compare Mérida vs Mexico City 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.