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SunnyDays

ERA5 almanac — 8 years of real data

Mexico City in May

Mexico City in May: 35% of days see measurable rain, 83°F average high, 33% of days historically clear (n=248, ERA5 2018–2025).

Mexico City in May is historically a poor month for sun: only 33% of days clear across 8 years (n=248, avg high 83°F). 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 Mexico City 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 Mexico City 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		 37% n=120 83°F
Late May
16th–end		 29% n=128 83°F
Full month average 33% n=248 83°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 Mexico City 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		 95% n=120
Late May
16th–end		 98% n=128
Full month average 97% n=248
12.5 h median sunshine per day 99% of days exceed 8 h sunshine 35% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 33%. Sunshine-based “warm & sunny”: 97%. The 64-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

Mexico City is mostly overcast in May historically: only 33% of days are clear across 8 years (n=248), avg high 83°F. Most visitors this month will see more clouds than sun.

Every month in Mexico City

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

Historical clear-sky % for Mexico City, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 52% n=248 All destinations →
February 71% n=226 All destinations →
March 71% n=248 All destinations →
April 51% n=240 All destinations →
May ← this page 33% n=248 All destinations →
June 18% n=240 All destinations →
July 1% n=248 All destinations →
August 2% n=248 All destinations →
September 4% n=240 All destinations →
October 20% n=248 All destinations →
November 52% n=240 All destinations →
December 50% n=248 All destinations →

Frequently asked

Does it rain in Mexico City in May?

Sometimes. Mexico City sees measurable rain on 35% of days in May historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Mexico City good for sun in May?

It's mixed. Mexico City in May is clear on 33% of days historically (avg high 83°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Mexico City compares in May

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