ERA5 almanac comparison — 8 years of real data
Costa Rica — Guanacaste vs Palm Beach: weather in September
Essentially a tie in September: Costa Rica — Guanacaste is 2% clear historically, Palm Beach is 6% clear (8-year ERA5 average) — within the noise. Avg high 88°F vs 86°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Costa Rica — Guanacaste
Costa Rica
- Clear days, September
- 2%
- Sample size
- n=240 days
- Avg high
- 88°F
- Early September (1st–15th)
- 3%
- Late September (16th–end)
- 2%
- Rain frequency
- 92% of days
Palm Beach
FL
- 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
Frequently asked
Is Costa Rica — Guanacaste or Palm Beach warmer in September?
Costa Rica — Guanacaste runs warmer by day in September. Costa Rica — Guanacaste averages highs of 88°F (highs n=240 days); Palm Beach averages highs of 86°F (highs n=240 days) (ERA5 2018–2025). Historical averages, not a forecast.
Does it rain more in Costa Rica — Guanacaste or Palm Beach in September?
Days with measurable rain: Costa Rica — Guanacaste 92%, Palm Beach 79% (n=240 and n=240 days). ERA5 2018–2025; historical, not a forecast.
Which is sunnier in September, Costa Rica — Guanacaste or Palm Beach?
Essentially a tie in September: Costa Rica — Guanacaste is 2% clear historically, Palm Beach is 6% clear (8-year ERA5 average) — within the noise. Avg high 88°F vs 86°F. Pick based on flight time or price, not weather — the weather won't decide this one for you.
Compare Costa Rica — Guanacaste 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 forecast for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.