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SunnyDays

ERA5 almanac — 8 years of real data

Oaxaca in May

Oaxaca in May: 30% of days see measurable rain, 86°F average high, 45% of days historically clear (n=248, ERA5 2018–2025).

Oaxaca in May is a mixed month for sun: 45% of days historically clear (n=248, avg high 86°F). The outcome varies year to year — check the early/late split below. 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 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 May

Clear-sky percentage for Oaxaca in May, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early May
1st–15th		 47% n=120 86°F
Late May
16th–end		 43% n=128 86°F
Full month average 45% n=248 86°F

Sunshine & warmth in May

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 May. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early May
1st–15th		 99% n=120
Late May
16th–end		 97% n=128
Full month average 98% n=248
12.5 h median sunshine per day 97% of days exceed 8 h sunshine 30% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 45%. Sunshine-based “warm & sunny”: 98%. The 53-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 in May is genuinely mixed: 45% of days historically clear (n=248), avg high 86°F — roughly even odds. The outcome varies year to year; don't book if you need guaranteed sun.

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 82% n=248 All destinations →
February 90% n=226 All destinations →
March 86% n=248 All destinations →
April 70% n=240 All destinations →
May ← this page 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 May?

Sometimes. Oaxaca sees measurable rain on 30% of days in May historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Oaxaca good for sun in May?

It's mixed. Oaxaca in May is clear on 45% of days historically (avg high 86°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Oaxaca compares in May

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.