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 April. 1  32. 32Â°C max day temperature. 2  8. 8 hours of sunshine per day. 3  3. 3 days with some rainfall. 4  21. 21Â°C min night temperature. 5  13. 13 hours of daylight per day. 6  H. High heat & humidity. 7  43. 43 mm of monthly rainfall. 8  11. 11+ (Extreme) UV index. 9  26. 26Â°C sea temperature.