Effects of high humidity. Humidity is considered too high when its level goes above 45% - 50%, sometimes as high as 80% and up. High humidity can be especially dangerous when combined with high temperature - as mentioned above, high humidity disrupts the body's ability to cool itself, which may lead to a heat stroke.
The average sea surface temperature in April 2017 for Cancun was 84.0Â°F. The maximum and minimum values were 83.0Â°F and 85.4Â°F respectively.
CLIMATE AND WEATHER STATISTICS FOR CANCUN. Cancun weather is fantastic year-round. High temperatures average in the high 80s, while lows are only in the 70s. The rainy season runs from May through October, while the dry season is November through April.ancun water temperatures are always bathtub warm, varying from 78 F-80 F in the winter months to 82 F-84 F in the summer months. Underwater visibility is best near Cozumel, where it can reach up to an amazing 200 feet.