Average Weather in Grytviken South Georgia & South Sandwich Islands
The climate in Grytviken is chilly, extremely windy, and overcast. Over the course of the year, the temperature typically varies from 26°F to 40°F and is rarely below 19°F or above 43°F.
Average High and Low Temperature
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
In Grytviken, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.
The clearer part of the year in Grytviken begins around October 1 and lasts for 6.1 months, ending around April 3. On December 16, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 37% of the time, and overcast or mostly cloudy 63% of the time.
The cloudier part of the year begins around April 3 and lasts for 5.9 months, ending around October 1. On June 21, the cloudiest day of the year, the sky is overcast or mostly cloudy 79% of the time, and clear, mostly clear, or partly cloudy 21% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Grytviken varies throughout the year.
The wetter season lasts 5.9 months, from November 17 to May 13, with a greater than 33% chance of a given day being a wet day. The chance of a wet day peaks at 44% on January 26.
The drier season lasts 6.1 months, from May 13 to November 17. The smallest chance of a wet day is 21% on October 5.
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 in Grytviken changes throughout the year.
Rain alone is the most common for 10 months, from August 22 to August 28 and from September 21 to July 26. The highest chance of a day with rain alone is 44% on January 26.
Mixed snow and rain is the most common for 1.5 months, from July 26 to August 22 and from September 3 to September 21. The highest chance of a day with mixed snow and rain is 10% on July 30.
Snow alone is the most common for 6.0 days, from August 28 to September 3. The highest chance of a day with snow alone is 10% on August 29.
Daily Chance of Precipitation
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. Grytviken experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Grytviken. The most rain falls during the 31 days centered around February 7, with an average total accumulation of 2.9 inches.
The least rain falls around August 4, with an average total accumulation of 0.7 inches.
Average Monthly Rainfall
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Grytviken experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 7.2 months, from April 22 to November 29, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around September 10, with an average total liquid-equivalent accumulation of 0.6 inches.
The snowless period of the year lasts for 4.8 months, from November 29 to April 22. The least snow falls around February 8, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Grytviken varies extremely over the course of the year. In 2017, the shortest day is June 21, with 7 hours, 19 minutes of daylight; the longest day is December 21, with 17 hours, 13 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 3:46 AM on December 14, and the latest sunrise is 5 hours, 3 minutes later at 8:48 AM on June 25. The earliest sunset is at 4:06 PM on June 17, and the latest sunset is 4 hours, 56 minutes later at 9:02 PM on December 28.
Daylight saving time (DST) is not observed in Grytviken during 2017.
Sunrise & Sunset with Twilight
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 Grytviken, 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, remaining a virtually constant 0% throughout.
Humidity Comfort Levels
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 Grytviken experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 4.7 months, from June 13 to November 5, with average wind speeds of more than 10.1 miles per hour. The windiest day of the year is August 29, with an average hourly wind speed of 11.0 miles per hour.
The calmer time of year lasts for 7.3 months, from November 5 to June 13. The calmest day of the year is December 22, with an average hourly wind speed of 9.2 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Grytviken is from the west throughout the year.
Grytviken 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 3.2 months, from January 10 to April 15, with an average temperature above 37°F. The day of the year with the warmest water is March 3, with an average temperature of 38°F.
The time of year with cooler water lasts for 4.1 months, from June 30 to November 4, with an average temperature below 34°F. The day of the year with the coolest water is September 8, with an average temperature of 32°F.
Average Water Temperature
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 extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 2.6 months, from November 11 to January 29, with an average daily incident shortwave energy per square meter above 4.4 kWh. The brightest day of the year is December 21, with an average of 5.4 kWh.
The darker period of the year lasts for 4.4 months, from April 14 to August 27, with an average daily incident shortwave energy per square meter below 1.4 kWh. The darkest day of the year is June 21, with an average of 0.4 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Grytviken are -54.281 deg latitude, -36.509 deg longitude, and 253 ft elevation.
The topography within 2 miles of Grytviken contains very significant variations in elevation, with a maximum elevation change of 1,926 feet and an average elevation above sea level of 570 feet. Within 10 miles contains very significant variations in elevation (7,513 feet). Within 50 miles also contains extreme variations in elevation (9,669 feet).
The area within 2 miles of Grytviken is covered by snow and glaciers (51%), water (24%), and shrubs (11%), within 10 miles by snow and glaciers (52%) and water (43%), and within 50 miles by water (83%) and snow and glaciers (16%).
This report illustrates the typical weather in Grytviken, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Grytviken is further than 200 kilometers from the nearest reliable weather station, so the weather-related data on this page were taken entirely from NASA's MERRA-2 satellite-era reanalysis . 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.
The temperature and dew point estimates are corrected for the difference between the reference elevation of the MERRA-2 grid cell and the elevation of Grytviken, according to the International Standard Atmosphere .
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.
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.