ERA5 almanac — 8 years of real data

Costa Rica — Guanacaste in November

Costa Rica — Guanacaste in November: rain frequency data not yet backfilled for this month, 86°F average high, 18% of days historically clear (n=240, ERA5 2018–2025).

Costa Rica — Guanacaste in November is historically a poor month for sun: only 18% of days clear across 8 years (n=240, avg high 86°F). February is the clearest month for Costa Rica — Guanacaste historically. Historical average, not a forecast.

What you are reading: 8-year historical averages from the ERA5 reanalysis, not a forecast. A month that is historically 90% clear can still be overcast on your specific trip. For this week’s actual forecast, see the live Costa Rica — Guanacaste page. Both can be true at once: “historically strong in this month; this particular week is not.” We label which is which.

Early vs. Late November

Clear-sky percentage for Costa Rica — Guanacaste in November, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period	% Clear days	Sample (n)	Avg high
Early November 1st–15th	10%	n=120	86°F
Late November 16th–end	25%	n=120	86°F
Full month average	18%	n=240	86°F

Bottom line

Costa Rica — Guanacaste is a poor choice for sun in November: just 18% of days clear historically (n=240). February is the historically strongest month for sun here. The 8-year record is consistent — this is not a fluke bad stretch.

→ See all destinations in February — historically the best month for sun in Costa Rica — Guanacaste.

Every month in Costa Rica — Guanacaste

Compare across all months with data. Numbers are historical clear-sky %.

Historical clear-sky % for Costa Rica — Guanacaste, all months, ERA5 2018–2025.
Month	% Clear	Sample (n)
January	79%	n=248	All destinations →
February	84%	n=226	All destinations →
March	70%	n=248	All destinations →
April	33%	n=240	All destinations →
May	9%	n=248	All destinations →
June	5%	n=240	All destinations →
July	16%	n=248	All destinations →
August	6%	n=248	All destinations →
September	2%	n=240	All destinations →
October	2%	n=248	All destinations →
November ← this page	18%	n=240	All destinations →
December	62%	n=248	All destinations →

Frequently asked

Is Costa Rica — Guanacaste good for sun in November?

Not usually. Costa Rica — Guanacaste is historically overcast in November: only 18% of days are clear (avg high 86°F, n=240 days, ERA5 2018–2025). February is historically far better for sun here.

→ Costa Rica — Guanacaste live forecast — this week’s actual 7-day weather, not historical
→ Best destinations in November — all destinations ranked by November clear-sky %
→ All destinations
→ Raw data (JSON) — buckets, n, source

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.