The water temperature in the US Virgin Islands does not vary drastically from summer to winter, but a difference of 4 or 5 degrees is noticeable for those who are used to a consistently warm tropical climate. During the summer months, the water temperature is around 83°F and in winter it drops to about 79°F. The Virgin Islands are hot, oppressive, windy and partly cloudy. Throughout the year, the temperature usually ranges from 74°F to 89°F and is rarely lower than 71°F or higher than 93°F.The Virgin Islands experience such little variation throughout the year that it's not really meaningful to talk about warm and cold seasons.
The figure below shows a compact year-round illustration of average temperatures per hour. The horizontal axis is the day of the year, the vertical axis is the time of day and the color is the average temperature of that time and day. The Virgin Islands, on average, have a sky covered by clouds that experiences extreme seasonal variations over the year. The clearest month of the year in the US Virgin Islands is January, during which, on average, the sky is clear, mostly clear or partly cloudy 82% of the time. The cloudiest month of the year in the US Virgin Islands is June, during which, on average, the sky is overcast or mostly cloudy 66% of the time. A humid day is one with at least 0.04 inches of liquid precipitation or liquid equivalent.
The chance of wet days in the US Virgin Islands varies throughout the year. The wettest season lasts 7.0 months, from May 2 to December 1, with a greater than 25% chance that a given day will be humid. The month with the most humid days in the US Virgin Islands is September, with an average of 11.5 days with at least 0.04 inches of precipitation. To show variation within months and not just monthly totals, we show cumulative rainfall during a 31-day moving period centered on each day of the year. The Virgin Islands experience significant seasonal variation in monthly rainfall. The month with the most rainfall in the US Virgin Islands is September, with an average rainfall of 3.7 inches.
The month with the least rainfall in the US Virgin Islands is March, with an average rainfall of 0.7 inches. The following figure presents a compact representation of Sun's elevation (the angle of Sun above horizon) and azimuth (the direction of compass) for each hour of each day of reporting period. The horizontal axis is day of year and vertical axis is time of day. For a given day and time on that day, background color indicates azimuth of sun at that time.
Black isolines are contours of constant solar elevation. We base humidity comfort level on dew point since it determines if perspiration evaporates from skin and thus cools body. Lower dew points feel drier and higher dew points feel wetter. Unlike temperature which tends to vary significantly between night and day, dew point tends to change more slowly so while temperature may drop at night, muggy day usually followed by humid night. The Virgin Islands experience some seasonal variation in perceived humidity. The muggiest period of year lasts 9.8 months, from March 28 to January 20, during which time comfort level embarrassing, oppressive or miserable at least 78% of time. The month with most humid days in US Virgin Islands is August with 30.8 muggy days or worse.
The month with least humid days in US Virgin Islands is February with 20.6 muggy days or worse. This section analyzes average wind vector per hour over wide area (speed and direction) 10 meters above ground. Wind experienced in given location depends largely on local topography and other factors and instantaneous speed and direction wind vary more than hourly averages. The average hourly wind speed in US Virgin Islands experiences significant seasonal variation throughout year. Windiest part of year lasts for 2.8 months from June 3 to August 30 with average wind speeds more than 13.9 miles per hour. The windiest month of year in US Virgin Islands is July with an average hourly wind speed 15.8 miles per hour. Predominant average hourly wind direction in US Virgin Islands is east all year round. US Virgin Islands located near large body water (e.g., ocean).
This section reports on average surface temperature that water over wide area. Average water temperature experiences some seasonal variation throughout year. Time of year with warmest waters lasts 3.4 months from July 30 to November 12 with an average temperature above 83°F. Month of year in US Virgin Islands with warmest water is September with an average temperature 84°F.Time of year when water coldest lasts 3.2 months from January 7 to April 14 with an average temperature below 80°F. US Virgin Islands with coldest water are February with an average temperature 79°F.To characterize how pleasant climate is in US Virgin Islands: Throughout year we calculated two travel scores.
Tourism score favors clear and rainless days with perceived temperatures between 65°F and 80°F. Based on this score best time of year to visit US Virgin Islands for general outdoor tourism activities range from late December to late March with comfortable temperatures and low chance for rain or snow.