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SunnyDays

ERA5 almanac — 8 years of real data

Oaxaca in January

Oaxaca in January: 2% of days see measurable rain, 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

Sunshine & warmth in January

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 Oaxaca in January. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early January
1st–15th		 95% n=120
Late January
16th–end		 93% n=128
Full month average 94% n=248
10.9 h median sunshine per day 100% of days exceed 8 h sunshine 2% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 82%. Sunshine-based “warm & sunny”: 94%. The 12-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

Oaxaca is historically one of the best 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

Does it rain in Oaxaca in January?

Rarely. Only 2% of days in Oaxaca see measurable rain in January, based on 8 years of ERA5 historical data (n=248 days, 2018–2025). This is a historical average, not a forecast.

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).

How Oaxaca compares in January

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Oaxaca 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.