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SunnyDays

ERA5 almanac — 8 years of real data

Cancún in October

Cancún in October: 70% of days see measurable rain, 85°F average high, 10% of days historically clear (n=248, ERA5 2018–2025).

Cancún in October is historically a poor month for sun: only 10% of days clear across 8 years (n=248, avg high 85°F). April is the clearest month for Cancún historically. 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 Cancún 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 October

Clear-sky percentage for Cancún in October, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early October
1st–15th		 5% n=120 85°F
Late October
16th–end		 15% n=128 85°F
Full month average 10% n=248 85°F

Sunshine & warmth in October

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 Cancún in October. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early October
1st–15th		 92% n=120
Late October
16th–end		 95% n=128
Full month average 94% n=248
11.0 h median sunshine per day 86% of days exceed 8 h sunshine 70% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 10%. Sunshine-based “warm & sunny”: 94%. The 84-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

Cancún is a poor choice for sun in October: just 10% of days clear historically (n=248). April is the historically strongest month for sun here. The 8-year record is consistent — this is not a fluke bad stretch.

→ See all destinations in April — historically the best month for sun in Cancún.

Every month in Cancún

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

Historical clear-sky % for Cancún, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 21% n=248 All destinations →
February 22% n=226 All destinations →
March 34% n=248 All destinations →
April 40% n=240 All destinations →
May 21% n=248 All destinations →
June 10% n=240 All destinations →
July 11% n=248 All destinations →
August 9% n=248 All destinations →
September 5% n=240 All destinations →
October ← this page 10% n=248 All destinations →
November 15% n=240 All destinations →
December 20% n=248 All destinations →

Frequently asked

Does it rain in Cancún in October?

Yes, frequently. In Cancún, 70% of days in October see measurable rain, based on 8 years of ERA5 historical data (n=248 days, 2018–2025). This is a historical average, not a forecast.

Is Cancún good for sun in October?

Not usually. Cancún is historically overcast in October: only 10% of days are clear (avg high 85°F, n=248 days, ERA5 2018–2025). April is historically far better for sun here.

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.