ERA5 almanac comparison — 8 years of real data
Cayman Islands vs St. Barthélemy: weather in October
St. Barthélemy edges out Cayman Islands for sun in October: 20% clear historically versus 5% (8-year ERA5 average, a 15-point gap). Cayman Islands also sees measurably more rain than St. Barthélemy this month (73% vs 57% of days). Both are viable — St. Barthélemy is the safer bet.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific October. For this
week’s actual forecast, each destination links to its live page below.
Cayman Islands
KY
- Clear days, October
- 5%
- Sample size
- n=248 days
- Avg high
- 86°F
- Early October (1st–15th)
- 6%
- Late October (16th–end)
- 4%
- Rain frequency
- 73% of days
St. Barthélemy
BL
- Clear days, October
- 20%
- Sample size
- n=248 days
- Avg high
- 83°F
- Early October (1st–15th)
- 21%
- Late October (16th–end)
- 20%
- Rain frequency
- 57% of days
Compare Cayman Islands vs St. Barthélemy 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.