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 year. 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%).
Over the course of a year, the temperature typically varies from 73°F to 89°F and is rarely below 71°F or above 93°F.
The warm season lasts from June 13 to September 22 with an average daily high temperature above 88°F. The hottest day of the year is August 3, with an average high of 89°F and low of 80°F.
The cold season lasts from December 10 to March 29 with an average daily high temperature below 85°F. The coldest day of the year is January 26, with an average low of 73°F and high of 84°F.
The length of the day varies significantly over the course of the year. The shortest day is December 21 with 11:01 hours of daylight; the longest day is June 20 with 13:13 hours of daylight.
The earliest sunrise is at 5:43am on June 1 and the latest sunset is at 7:01pm on July 5. The latest sunrise is at 6:55am on January 22 and the earliest sunset is at 5:41pm on November 24.
Daylight savings time (DST) is not observed in 2012.
The median cloud cover is 21% (mostly clear) and does not vary substantially over the course of the year.
On July 13, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 57% of the time, and overcast or mostly cloudy 17% of the time.
On December 6, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 26% of the time, and clear or mostly clear 51% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around November 3, occurring in 37% of days. Precipitation is least likely around April 1, occurring in 23% of days.
Over the entire year, the most common forms of precipitation are light rain, moderate rain, and heavy rain.
Light rain is the most severe precipitation observed during 47% of those days with precipitation. It is most likely around December 21, when it is observed during 17% of all days.
Moderate rain is the most severe precipitation observed during 26% of those days with precipitation. It is most likely around October 31, when it is observed during 11% of all days.
Heavy rain is the most severe precipitation observed during 21% of those days with precipitation. It is most likely around October 26, when it is observed during 10% of all days.
During the warm season, which lasts from June 13 to September 22, there is a 30% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light rain (45% of days with precipitation have at worst light rain), moderate rain (25%), heavy rain (21%), and thunderstorms (9%).
During the cold season, which lasts from December 10 to March 29, there is a 28% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light rain (53% of days with precipitation have at worst light rain), moderate rain (28%), and heavy rain (17%).
Either snow is exceptionally unlikely to fall at any time during the year at this location or this station does not reliably report precipitation types.
The relative humidity typically ranges from 56% (mildly humid) to 87% (very humid) over the course of the year, rarely dropping below 45% (comfortable) and reaching as high as 97% (very humid).
The air is driest around March 2, at which time the relative humidity drops below 60% (mildly humid) three days out of four; it is most humid around November 7, exceeding 83% (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 year, the dew point typically varies from 64°F (mildy humid) to 76°F (oppressive) and is rarely below 58°F (comfortable) or above 79°F (oppressive).
Over the course of the year typical wind speeds vary from 5 mph to 18 mph (light breeze to fresh breeze), rarely exceeding 22 mph (fresh breeze).
The highest average wind speed of 12 mph (moderate breeze) occurs around June 26, at which time the average daily maximum wind speed is 18 mph (moderate breeze).
The lowest average wind speed of 9 mph (gentle breeze) occurs around October 23, at which time the average daily maximum wind speed is 15 mph (moderate breeze).