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Average Weather in Castries St. Lucia

The climate in Castries is hot, oppressive, extremely windy, and mostly cloudy. Over the course of the year, the temperature typically varies from 75°F to 87°F and is rarely below 72°F or above 89°F.

Average High and Low Temperature

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature

Average Hourly Temperature in Castries12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDecwarmwarmhothot
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.


In Castries, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Castries begins around November 26 and lasts for 4.4 months, ending around April 9. On January 13, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 60% of the time, and overcast or mostly cloudy 40% of the time.

The cloudier part of the year begins around April 9 and lasts for 7.6 months, ending around November 26. On September 27, the cloudiest day of the year, the sky is overcast or mostly cloudy 71% of the time, and clear, mostly clear, or partly cloudy 29% of the time.

Cloud Cover

Cloud Cover in Castriesclearerclearerclearerclearercloudiercloudier0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecSep 2771%Sep 2771%Jan 1340%Jan 1340%Nov 2655%Nov 2655%Apr 956%Apr 956%overcastovercastmostly cloudymostly cloudypartly cloudypartly cloudymostly clearmostly clearclearclear
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.


A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Castries varies throughout the year.

The wetter season lasts 6.3 months, from May 31 to December 10, with a greater than 33% chance of a given day being a wet day. The chance of a wet day peaks at 47% on November 9.

The drier season lasts 5.7 months, from December 10 to May 31. The smallest chance of a wet day is 18% on March 3.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 47% on November 9.

Daily Chance of Precipitation

Daily Chance of Precipitation in Castrieswetwetdrydrydrydry0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecNov 947%Nov 947%Mar 318%Mar 318%Jan 129%Jan 129%May 3133%May 3133%rainrain
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).


To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Castries experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year in Castries. The most rain falls during the 31 days centered around October 1, with an average total accumulation of 7.2 inches.

The least rain falls around February 16, with and average total accumulation of 1.7 inches.

Average Monthly Rainfall

Average Monthly Rainfall in Castries0 in2 in4 in6 in8 in10 in12 inJanFebMarAprMayJunJulAugSepOctNovDecOct 17.2 inOct 17.2 inFeb 161.7 inFeb 161.7 in
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.


The length of the day in Castries varies over the course of the year. In 2017, the shortest day is December 21, with 11 hours, 18 minutes of daylight; the longest day is June 21, with 12 hours, 57 minutes of daylight.

Hours of Daylight and Twilight

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 5:34 AM on June 1, and the latest sunrise is 57 minutes later at 6:32 AM on January 22. The earliest sunset is at 5:32 PM on November 20, and the latest sunset is 1 hour, 4 minutes later at 6:36 PM on July 8.

Daylight saving time (DST) is not observed in Castries during 2017.

Sunrise & Sunset with Twilight

Sunrise & Sunset with Twilight in Castries12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDecJun 15:34 AMJun 15:34 AM6:36 PMJul 86:36 PMJul 8Nov 205:32 PMNov 205:32 PM6:32 AMJan 226:32 AMJan 22daydaynightnightnightnight
The solar day over the course of the year 2017. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.


We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The perceived humidity level in Castries, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 2% of 98% throughout.

Humidity Comfort Levels

Humidity Comfort Levels in Castries0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecFeb 2896%Feb 2896%100%Aug 11100%Aug 11miserablemiserableoppressiveoppressivemuggymuggy
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.


This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Castries experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 8.5 months, from November 26 to August 10, with average wind speeds of more than 8.3 miles per hour. The windiest day of the year is June 22, with an average hourly wind speed of 9.6 miles per hour.

The calmer time of year lasts for 3.5 months, from August 10 to November 26. The calmest day of the year is October 2, with an average hourly wind speed of 7.0 miles per hour.

Average Wind Speed

Average Wind Speed in Castrieswindywindywindywindy0 mph1 mph2 mph3 mph4 mph5 mph6 mph7 mph8 mph9 mph10 mph11 mphJanFebMarAprMayJunJulAugSepOctNovDecJun 229.6 mphJun 229.6 mphOct 27.0 mphOct 27.0 mphNov 268.3 mphNov 268.3 mphAug 108.3 mphAug 108.3 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Castries is from the east throughout the year.

Wind Direction

Wind Direction in Castries0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecsouthsoutheasteastnorthnorth
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

Castries is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences some seasonal variation over the course of the year.

The time of year with warmer water lasts for 3.1 months, from August 11 to November 14, with an average temperature above 83°F. The day of the year with the warmest water is September 14, with an average temperature of 84°F.

The time of year with cooler water lasts for 3.2 months, from January 9 to April 15, with an average temperature below 81°F. The day of the year with the coolest water is February 20, with an average temperature of 80°F.

Average Water Temperature

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.

The brighter period of the year lasts for 2.5 months, from February 28 to May 11, with an average daily incident shortwave energy per square meter above 6.6 kWh. The brightest day of the year is April 2, with an average of 7.1 kWh.

The darker period of the year lasts for 2.8 months, from September 14 to December 9, with an average daily incident shortwave energy per square meter below 5.2 kWh. The darkest day of the year is October 12, with an average of 4.7 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in Castriesbrightbrightdarkdark0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWhJanFebMarAprMayJunJulAugSepOctNovDecApr 27.1 kWhApr 27.1 kWhOct 124.7 kWhOct 124.7 kWhFeb 286.6 kWhFeb 286.6 kWhMay 116.6 kWhMay 116.6 kWhDec 95.2 kWhDec 95.2 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.


For the purposes of this report, the geographical coordinates of Castries are 13.996 deg latitude, -61.006 deg longitude, and 43 ft elevation.

The topography within 2 miles of Castries contains very significant variations in elevation, with a maximum elevation change of 853 feet and an average elevation above sea level of 147 feet. Within 10 miles contains very significant variations in elevation (3,025 feet). Within 50 miles contains large variations in elevation (3,993 feet).

The area within 2 miles of Castries is covered by water (56%), trees (20%), and artificial surfaces (10%), within 10 miles by water (63%) and trees (26%), and within 50 miles by water (95%).

Data Sources

This report illustrates the typical weather in Castries, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Castries.

For each station, the records are corrected for the elevation difference between that station and Castries according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Castries is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Castries and a given station.

The stations contributing to this reconstruction are: Hewanorra International Airport (79%, 28 kilometers, south) and Martinique Aimé Césaire International Airport (21%, 67 kilometers, north).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for aiports and weather stations are provided by AskGeo.com .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.