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SunnyDays

ERA5 almanac — 8 years of real data

Costa Rica — Manuel Antonio in December

Costa Rica — Manuel Antonio in December: 45% of days see measurable rain, 83°F average high, 22% of days historically clear (n=248, ERA5 2018–2025).

Costa Rica — Manuel Antonio in December is historically a poor month for sun: only 22% of days clear across 8 years (n=248, avg high 83°F). February is the clearest month for Costa Rica — Manuel Antonio 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 — Manuel Antonio 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 December

Clear-sky percentage for Costa Rica — Manuel Antonio in December, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early December
1st–15th		 18% n=120 83°F
Late December
16th–end		 26% n=128 83°F
Full month average 22% n=248 83°F

Sunshine & warmth in December

A second measure using actual sunshine hours (ERA5 sunshine_duration), not the daily weather code. A Lowcountry day with 12 hours of sun and a 25-minute afternoon storm is counted below as a warm, sunny day — because it was. How we define this.

Sunshine-based metrics for Costa Rica — Manuel Antonio in December. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early December
1st–15th		 92% n=120
Late December
16th–end		 91% n=128
Full month average 91% n=248
11.0 h median sunshine per day 88% of days exceed 8 h sunshine 45% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 22%. Sunshine-based “warm & sunny”: 91%. The 69-point gap is from brief afternoon convective storms that stamp the whole day as “rain” in the WMO code but leave the bulk of the sunshine untouched.

Bottom line

Costa Rica — Manuel Antonio is mostly overcast in December historically: only 22% of days are clear across 8 years (n=248), avg high 83°F. If you want sun in Costa Rica — Manuel Antonio, February is historically much better. Most visitors this month will see more clouds than sun.

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

Every month in Costa Rica — Manuel Antonio

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

Historical clear-sky % for Costa Rica — Manuel Antonio, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 37% n=248 All destinations →
February 51% n=226 All destinations →
March 34% n=248 All destinations →
April 8% n=240 All destinations →
May 4% n=248 All destinations →
June 2% n=240 All destinations →
July 5% n=248 All destinations →
August 3% n=248 All destinations →
September 0% n=240 All destinations →
October 0% n=248 All destinations →
November 4% n=240 All destinations →
December ← this page 22% n=248 All destinations →

Frequently asked

Does it rain in Costa Rica — Manuel Antonio in December?

Sometimes. Costa Rica — Manuel Antonio sees measurable rain on 45% of days in December historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Costa Rica — Manuel Antonio good for sun in December?

Not usually. Costa Rica — Manuel Antonio is historically overcast in December: only 22% of days are clear (avg high 83°F, n=248 days, ERA5 2018–2025). February is historically far better for sun here.

How Costa Rica — Manuel Antonio compares in December

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Costa Rica — Manuel Antonio this month — same passport tier, similar flight distance, both sides from the same 8-year ERA5 record.

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.