ERA5 almanac — 8 years of real data

Mexico City in May

Mexico City in May: rain frequency data not yet backfilled for this month, 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

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

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.

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