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SunnyDays

ERA5 almanac — 8 years of real data

Cancún in August

Cancún in August: 63% of days see measurable rain, 88°F average high, 9% of days historically clear (n=248, ERA5 2018–2025).

Cancún in August is historically a poor month for sun: only 9% of days clear across 8 years (n=248, avg high 88°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 August

Clear-sky percentage for Cancún in August, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early August
1st–15th		 6% n=120 88°F
Late August
16th–end		 12% n=128 88°F
Full month average 9% n=248 88°F

Sunshine & warmth in August

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 August. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early August
1st–15th		 99% n=120
Late August
16th–end		 96% n=128
Full month average 97% n=248
12.0 h median sunshine per day 96% of days exceed 8 h sunshine 63% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 9%. Sunshine-based “warm & sunny”: 97%. The 88-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 August: just 9% 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 ← this page 9% n=248 All destinations →
September 5% n=240 All destinations →
October 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 August?

Yes, frequently. In Cancún, 63% of days in August 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 August?

Not usually. Cancún is historically overcast in August: only 9% of days are clear (avg high 88°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.