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 January. 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 January is characterized by essentially constant daily high temperatures, with daily highs around 84°F throughout the month, exceeding 87°F or dropping below 81°F only one day in ten.
Over the course of January, the length of the day is essentially constant. The shortest day of the month is January 6 with 11:04 hours of daylight; the longest day is January 31 with 11:20 hours of daylight.
The earliest sunrise is at 6:51am on January 1; the latest sunset is at 6:14pm on January 31; the latest sunrise is at 6:55am on January 22; the earliest sunset is at 5:55pm on January 1.
Daylight savings time (DST) is not observed in 2012.
The median cloud cover is 23% (mostly clear) and does not vary substantially over the course of the month.
On January 16, a representative day, the sky is clear or mostly clear 52% of the time, partly cloudy 6% of the time, and mostly cloudy or overcast 17% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around January 5, occurring in 32% of days. Precipitation is least likely around January 31, occurring in 27% of days.
Throughout January, the most common forms of precipitation are light rain, moderate rain, and heavy rain.
Light rain is the most severe precipitation observed during 54% of those days with precipitation. It is most likely around January 1, when it is observed during 17% of all days.
Moderate rain is the most severe precipitation observed during 28% of those days with precipitation. It is most likely around January 8, when it is observed during 9% of all days.
Heavy rain is the most severe precipitation observed during 16% of those days with precipitation. It is most likely around January 2, when it is observed during 6% of all days.
Either snow is exceptionally unlikely to fall at this location in January or this station does not reliably report precipitation types.
The relative humidity typically ranges from 57% (mildly humid) to 85% (humid) over the course of a typical January, rarely dropping below 48% (comfortable), or exceeding 94% (very humid).
The air is driest around January 30, at which time the relative humidity drops below 62% (mildly humid) three days out of four; it is most humid around January 1, rising above 81% (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 January, the dew point typically varies from 65°F (mildy humid) to 71°F (muggy) and is rarely below 60°F (comfortable) or above 74°F (very muggy).
Over the course of January typical wind speeds vary from 6 mph to 17 mph (light breeze to moderate breeze), rarely exceeding 22 mph (fresh breeze).
The highest average wind speed of 11 mph (gentle breeze) occurs around January 28, 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 January 1, at which time the average daily maximum wind speed is 17 mph (moderate breeze).