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

Cozumel weather in September historically has hot temperatures and much higher rainfall than usual.

These averages make it clear that going to Mexico’s largest island for vacation is a risky bet in September.

September is normally the most active month of the Caribbean hurricane season. Historically, the region averages three to four hurricanes and tropical storms in September with two that often become major hurricanes.

But heavy rains that hit Cozumel during the month don’t stop some vacationers from going there.

Many of them either don’t know about the risk or do know about it and take advantage of last-minute vacations with a clear short-term weather forecast. Last-minute visitors are likely to find low prices at island hotels and resorts because it is the off season.

Rainfall in September

The historical average of 9.5 inches of rain in September for Cozumel is almost the same amount the island normally has in October, according to Servicio Meteorológico Nacional, Mexico’s national meteorology service. September and October are the worst months of the Cozumel hurricane season.

By comparison, the island averages less than two inches of rainfall in March and April during the dry season.

It rains an average of 15 days in September compared to 16 days in October. It rains only four days during a typical March or April.

Total rainfall in Cozumel during September is one of the highest in the Caribbean.

Temperatures in September

Cozumel temperatures in September have an average high of 89 degrees Fahrenheit or about 32 Celsius, according to Servicio Meteorológico Nacional. It is summer-like weather that begins in April every year. The first half of September is slightly warmer than the second half as fall weather begins to approach.

By comparison, daytime temperatures average in the low 80s Fahrenheit or high 20s Celsius during the winter.

The average low temperature in September of 75 degrees Fahrenheit or 24 Celsius usually takes place at night. Seawater temperatures hover about midway between the daily highs and nighttime lows with temperatures warmest in mid to late afternoons.

• Cozumel weather in: January, February, March, April, May, June, July, August, September, October, November, December