The highest day temperature in May 2025 was 86°F. The lowest night temperature was 78°F. The average values for day and night temperatures during May were 83.7°F и 81.5°F respectivly.

The average sea surface temperature in May 2025 for Cayo Guillermo was 85.8°F. The maximum and minimum values were 82.0°F and 88.2°F respectively.

Most of the days in May are cloudy but you can also expect sunny or gloomy days.

Precipitation total in May for Cayo Guillermo is 4.5 in. It makes may the most rainy month of the year.

The average wind speed in May is 12.6 mph.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Cayo Guillermo in May is 7.8 hours.