Weather in Cancun in September

How September compares

September is the 3rd warmest month of the year in Cancun and ranks 27th of 134 destinations we compare for September - see where else is hot in September. Within Mexico it is 5th of 5 (Mexico in September). Against London's average high of 18.6°C in September, Cancun is 10.7°C warmer by day and 14.6°C warmer at night.

Daytime and night-time in September

The typical September day in Cancun peaks at 29.3°C, but that is an average: the warmest 10% of days reach 30.6°C or more. About 100% of days top 25°C and 1 in 4 pass 30°C. Nights average 25.8°C; one night in ten drops to 24.6°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest September day here reached 32.0°C (2019-09-15) and the coldest night 22.6°C (1994-09-22).

Rain in September

Wet (more than 8 rainy days): about 25 days with 1 mm or more, 206 mm in total. Year to year it varies a lot - the wettest September was 2013 with 423 mm, the driest 1996 with 92 mm. Humidity averages 83%, which makes the heat feel heavier than the thermometer suggests.

Sea temperature in September

The sea averages 28.9°C - warm enough to swim (22°c+). Depending on the year it ranges from 28.4°C to 29.3°C. This is the warmest the sea gets here all year.

Sunshine and daylight

Around 4.6 hours of sunshine a day (estimated from cloud cover), 12.1 hours of daylight: the sun rises about 06:35 and sets about 18:51 local time in mid-September. Average cloud cover is 62%.

Is September a good time to visit Cancun?

It is a reasonable choice: hot days but expect showers. The best months for Cancun on our scoring are April, March, February; months averaging 25°C or more: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec.

Hot days, warm nights and a sea made for swimming

The heat is dependable; feeling cool is less so. Humidity averages 83%, which can make time outside feel sticky even when temperatures do not look extreme. Choose loose, lightweight clothing and avoid putting your most active plans around midday. Evenings offer little relief from the warmth, so air conditioning is a sensible accommodation priority rather than something to overlook. The sea averages 28.9°C, making it comfortable for swimming on temperature alone, though that does not guarantee suitable conditions whenever you want to get in. This weather suits people happy to alternate swimming with shade and indoor breaks, rather than those who prefer crisp evenings or long, energetic days outside.

Rain is the main compromise

With rain on about 25 days, wet weather needs to be part of your plan rather than treated as an unlikely interruption. That does not mean continuous rain, but the figures do not promise brief showers or a reliably dry part of the day either. Keep outdoor plans movable and pack a light waterproof that will not feel too heavy in the heat. Sunshine averages 4.6 hours daily, so there is scope for bright spells without a strong case for expecting clear skies throughout. September makes sense if warmth matters more than sunshine and you can enjoy a slower day indoors. If rain would leave you regretting the trip, choose another month.