Average high temperature and rainfall for Cancun in September. © Scott S. Bateman

Cancun weather in September is risky for anyone who wants to visit this major resort city on the Caribbean coast of Mexico.

Cancun is popular because of great attractions, cheap airline flights and easy access for visitors from the midwestern, eastern and southern United States. It also is popular especially from December through May each year because of warm weather and low risk of rain.

But September historically is the worst weather month of the year for Cancun because of heavy annual rains.

Rain in September

The risk of rain climbs from a low point in late winter to a high point in early fall. Cancun’s average rainfall of 10 inches during September is the highest of the year, according to Servicio Meteorológico Nacional, Mexico’s government meteorology service. It is a big change from the one to two inches a month from February through April.

October has slightly less rain than September at a total of nine inches. Both months have high rainfall historically because they are the peak months of the annual Caribbean hurricane season. Although tropical storms and hurricanes rarely hit Cancun directly, they often pass nearby in the region.

The city averages about 14 days with rain during the month, which is better than the 16 days in October. Even so, when it does rain, it often rains a lot.

The high risk of rain makes September the worst month of the year to visit Cancun. Daring vacationers may go then because of cheap hotel prices. They also consider last-minute vacations if they see the short-term weather forecast shows a low risk of rain.

Cancun Temperatures in September

Temperatures stay hot despite the fact that the fall season begins during the month. Cancun temperatures in September have an average daytime high of 91 degrees Fahrenheit or about 33 Celsius, according to Servicio Meteorológico Nacional. This temperature is about the same as May through August.

The average low temperature, which mostly occurs at night, is 76 degrees Fahrenheit or about 24 Celsius. The hot daytime temperatures and moderate nighttime temperatures make seawater comfortable for swimming throughout the day, unlike the cooler winter months which at times have chilly seawater.

By comparison, the average high temperature for Cancun in the winter is in the low 80s Fahrenheit or mid 20s Celsius.

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