This report describes the typical weather at the Cyril E. King Airport (St. Thomas, US Virgin Islands) weather station over the course of an average May. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
St. Thomas has a tropical savanna climate with dry winters. The area within 25 mi of this station is covered by oceans and seas (99%).
The month of May is characterized by gradually rising daily high temperatures, with daily highs around 87°F throughout the month, exceeding 91°F or dropping below 83°F only one day in ten.
Over the course of May, the length of the day is essentially constant. The shortest day of the month is May 1 with 12:48 hours of daylight; the longest day is May 31 with 13:10 hours of daylight.
The earliest sunrise is at 5:43am on May 30; the latest sunset is at 6:53pm on May 31; the latest sunrise is at 5:53am on May 1; the earliest sunset is at 6:41pm on May 1.
Daylight savings time (DST) is not observed in 2012.
The median cloud cover is 22% (mostly clear) and does not vary substantially over the course of the month.
On May 16, a representative day, the sky is clear or mostly clear 48% of the time, partly cloudy 6% of the time, and mostly cloudy or overcast 21% of the time.
The average probability that some form of precipitation will be observed in a given day is 26%, with little variation over the course of the month.
Throughout May, the most common forms of precipitation are light rain, moderate rain, and heavy rain.
Light rain is the most severe precipitation observed during 51% of those days with precipitation. It is most likely around May 27, when it is observed during 14% of all days.
Moderate rain is the most severe precipitation observed during 23% of those days with precipitation. It is most likely around May 24, when it is observed during 6% of all days.
Heavy rain is the most severe precipitation observed during 20% of those days with precipitation. It is most likely around May 20, when it is observed during 5% of all days.
Either snow is exceptionally unlikely to fall at this location in May or this station does not reliably report precipitation types.
The relative humidity typically ranges from 61% (mildly humid) to 85% (humid) over the course of a typical May, rarely dropping below 52% (mildly humid), or exceeding 95% (very humid).
The air is driest around May 1, at which time the relative humidity drops below 65% (mildly humid) three days out of four; it is most humid around May 14, rising above 79% (humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a typical May, the dew point typically varies from 69°F (muggy) to 75°F (very muggy) and is rarely below 65°F (mildy humid) or above 78°F (oppressive).
Over the course of May typical wind speeds vary from 6 mph to 17 mph (light breeze to moderate breeze), rarely exceeding 21 mph (fresh breeze).
The highest average wind speed of 11 mph (gentle breeze) occurs around May 31, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 11 mph (gentle breeze) occurs around May 1, at which time the average daily maximum wind speed is 17 mph (moderate breeze).