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.
Key weather averages for Cancun in February. 1  28. 28Â°C max day temperature. 2  7. 7 hours of sunshine per day. 3  5. 5 days with some rainfall. 4  18. 18Â°C min night temperature. 5  11. 11 hours of daylight per day. 6  M. Moderate heat & humidity. 7  55. 55 mm of monthly rainfall. 8  9. 9 (Very High) UV index. 9  26. 26Â°C sea temperature.