ERA5 almanac comparison — 8 years of real data
Cancún vs St. Martin: weather in August
St. Martin edges out Cancún for sun in August: 16% clear historically versus 9% (8-year ERA5 average, a 7-point gap). Cancún also sees measurably more rain than St. Martin this month (63% vs 48% of days). Both are viable — St. Martin is the safer bet.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific August. For this
week’s actual forecast, each destination links to its live page below.
Cancún
MX
- Clear days, August
- 9%
- Sample size
- n=248 days
- Avg high
- 88°F
- Early August (1st–15th)
- 6%
- Late August (16th–end)
- 12%
- Rain frequency
- 63% of days
St. Martin
SX
- Clear days, August
- 16%
- Sample size
- n=248 days
- Avg high
- 80°F
- Early August (1st–15th)
- 13%
- Late August (16th–end)
- 19%
- Rain frequency
- 48% of days
Compare Cancún vs St. Martin 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.