ERA5 almanac comparison — 8 years of real data
Costa Rica — Guanacaste vs Sea Island: weather in June
Sea Island edges out Costa Rica — Guanacaste for sun in June: 24% clear historically versus 5% (8-year ERA5 average, a 19-point gap). Costa Rica — Guanacaste also sees measurably more rain than Sea Island this month (88% vs 52% of days). Both are viable — Sea Island is the safer bet.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific June. For this
week’s actual forecast, each destination links to its live page below.
Costa Rica — Guanacaste
CR
- Clear days, June
- 5%
- Sample size
- n=240 days
- Avg high
- 87°F
- Early June (1st–15th)
- 1%
- Late June (16th–end)
- 9%
- Rain frequency
- 88% of days
Sea Island
GA
- Clear days, June
- 24%
- Sample size
- n=240 days
- Avg high
- 85°F
- Early June (1st–15th)
- 24%
- Late June (16th–end)
- 25%
- Rain frequency
- 52% of days
Compare Costa Rica — Guanacaste vs Sea Island 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.