ERA5 almanac — 8 years of real data

Oaxaca in January

Oaxaca in January: rain frequency data not yet backfilled for this month, 79°F average high, 82% of days historically clear (n=248, ERA5 2018–2025).

Historically one of the better months to visit Oaxaca for sun: 82% of days are clear on average (n=248, avg high 79°F). Every percentage here is a historical average from 8 years of ERA5 data — 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 Oaxaca 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 January

Clear-sky percentage for Oaxaca in January, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period	% Clear days	Sample (n)	Avg high
Early January 1st–15th	82%	n=120	79°F
Late January 16th–end	82%	n=128	79°F
Full month average	82%	n=248	79°F

Bottom line

Oaxaca is historically one of the best US destinations for sun in January: 82% of days meet the clear bar (avg high 79°F, n=248 days across 8 years). Pack for outdoor activity — this month consistently delivers.

Every month in Oaxaca

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

Historical clear-sky % for Oaxaca, all months, ERA5 2018–2025.
Month	% Clear	Sample (n)
January ← this page	82%	n=248	All destinations →
February	90%	n=226	All destinations →
March	86%	n=248	All destinations →
April	70%	n=240	All destinations →
May	45%	n=248	All destinations →
June	16%	n=240	All destinations →
July	9%	n=248	All destinations →
August	6%	n=248	All destinations →
September	6%	n=240	All destinations →
October	28%	n=248	All destinations →
November	68%	n=240	All destinations →
December	84%	n=248	All destinations →

Frequently asked

Is Oaxaca good for sun in January?

Yes. Oaxaca is historically strong for sun in January: 82% of days are clear on average (avg high 79°F, n=248 days, ERA5 2018–2025).

→ Oaxaca live forecast — this week’s actual 7-day weather, not historical
→ Best destinations in January — all destinations ranked by January 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.