ERA5 almanac comparison — 8 years of real data

Mérida vs Palm Beach: weather in September

Essentially a tie in September: Mérida is 8% clear historically, Palm Beach is 6% clear (8-year ERA5 average) — within the noise. Avg high 92°F vs 86°F. Palm Beach also sees measurably more rain than Mérida this month (79% vs 60% of days). Pick based on flight time or price, not weather — the weather won't decide this one for you.

What you are reading: 8-year historical averages, not a forecast. Either destination can still surprise you this specific September. For this week’s actual forecast, each destination links to its live page below.

Mérida

Clear days, September: 8%
Sample size: n=240 days
Avg high: 92°F
Early September (1st–15th): 8%
Late September (16th–end): 9%
Rain frequency: 60% of days

Palm Beach

Clear days, September: 6%
Sample size: n=240 days
Avg high: 86°F
Early September (1st–15th): 5%
Late September (16th–end): 8%
Rain frequency: 79% of days

Compare Mérida vs Palm Beach 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.