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SunnyDays

ERA5 almanac — 8 years of real data

Huatulco in May

Huatulco in May: 42% of days see measurable rain, 90°F average high, 40% of days historically clear (n=248, ERA5 2018–2025).

Huatulco in May is a mixed month for sun: 40% of days historically clear (n=248, avg high 90°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 Huatulco 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 Huatulco 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		 54% n=120 90°F
Late May
16th–end		 27% n=128 90°F
Full month average 40% n=248 90°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 Huatulco 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		 100% n=120
Late May
16th–end		 96% n=128
Full month average 98% n=248
12.2 h median sunshine per day 96% of days exceed 8 h sunshine 42% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 40%. Sunshine-based “warm & sunny”: 98%. The 58-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

Huatulco in May is genuinely mixed: 40% of days historically clear (n=248), avg high 90°F — more cloudy than clear. The two halves differ materially (54% early, 27% late) — favour the early half of the month. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Huatulco

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

Historical clear-sky % for Huatulco, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 69% n=248 All destinations →
February 68% n=226 All destinations →
March 75% n=248 All destinations →
April 67% n=240 All destinations →
May ← this page 40% n=248 All destinations →
June 7% n=240 All destinations →
July 12% n=248 All destinations →
August 5% n=248 All destinations →
September 4% n=240 All destinations →
October 9% n=248 All destinations →
November 36% n=240 All destinations →
December 68% n=248 All destinations →

Frequently asked

Does it rain in Huatulco in May?

Sometimes. Huatulco sees measurable rain on 42% of days in May historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Huatulco good for sun in May?

It's mixed. Huatulco in May is clear on 40% of days historically (avg high 90°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Huatulco compares in May

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