ERA5 almanac comparison — 8 years of real data
Aruba vs Costa Rica — Manuel Antonio: weather in September
Aruba is the clear winner for sun in September: 32% of days historically clear versus just 0% in Costa Rica — Manuel Antonio — a 32-point gap across 8 years of ERA5 data. Costa Rica — Manuel Antonio also sees measurably more rain than Aruba this month (92% vs 27% of days). This isn't close.
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.
Aruba
AW
- Clear days, September
- 32%
- Sample size
- n=240 days
- Avg high
- 90°F
- Early September (1st–15th)
- 36%
- Late September (16th–end)
- 27%
- Rain frequency
- 27% of days
Costa Rica — Manuel Antonio
CR
- Clear days, September
- 0%
- Sample size
- n=240 days
- Avg high
- 83°F
- Early September (1st–15th)
- 0%
- Late September (16th–end)
- 0%
- Rain frequency
- 92% of days
Compare Aruba vs Costa Rica — Manuel 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 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.