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.
Cancun: Annual Weather Averages. June is the hottest month in Cancun with an average temperature of 28Â°C (82Â°F) and the coldest is January at 23Â°C (73Â°F) with the most daily sunshine hours at 11 in August. The wettest month is September with an average of 270mm of rain.