Average Weather in December in Grytviken South Georgia & South Sandwich Islands
Daily high temperatures increase by 2°F, from 36°F to 38°F, rarely falling below 33°F or exceeding 41°F.
Daily low temperatures increase by 2°F, from 33°F to 34°F, rarely falling below 30°F or exceeding 37°F.
For reference, on February 24, the hottest day of the year, temperatures in Grytviken typically range from 36°F to 40°F, while on July 24, the coldest day of the year, they range from 26°F to 31°F.
Average High and Low Temperature in December
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on December. The horizontal axis is the day, 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 December
The month of December in Grytviken experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 65% throughout the month. The lowest chance of overcast or mostly cloudy conditions is 63% on December 16.
The clearest day of the month is December 16, with clear, mostly clear, or partly cloudy conditions 37% of the time.
For reference, on June 21, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 79%, while on December 16, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 37%.
Cloud Cover Categories in December
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Grytviken, the chance of a wet day over the course of December is rapidly increasing, starting the month at 32% and ending it at 39%.
For reference, the year's highest daily chance of a wet day is 44% on January 26, and its lowest chance is 21% on October 5.
Over the course of December in Grytviken, the chance of a day with only rain increases from 29% to 38%, the chance of a day with mixed snow and rain remains an essentially constant 1% throughout, and the chance of a day with only snow remains an essentially constant 1% throughout.
Probability of Precipitation in December
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during December in Grytviken is gradually increasing, starting the month at 1.7 inches, when it rarely exceeds 2.6 inches or falls below 1.0 inches, and ending the month at 2.1 inches, when it rarely exceeds 3.0 inches or falls below 1.3 inches.
Average Monthly Rainfall in December
Over the course of December in Grytviken, the length of the day is gradually increasing. From the start to the end of the month, the length of the day increases by 20 minutes, implying an average daily increase of 40 seconds, and weekly increase of 4 minutes, 41 seconds.
The shortest day of the month is December 1, with 16 hours, 46 minutes of daylight and the longest day is December 21, with 17 hours, 13 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Grytviken is 3:46 AM on December 15 and the latest sunrise is 9 minutes later at 3:55 AM on December 31.
The earliest sunset is 8:38 PM on December 1 and the latest sunset is 24 minutes later at 9:02 PM on December 28.
Daylight saving time is not observed in Grytviken during 2018.
For reference, on December 21, the longest day of the year, the Sun rises at 3:47 AM and sets 17 hours, 13 minutes later, at 9:00 PM, while on June 21, the shortest day of the year, it rises at 8:48 AM and sets 7 hours, 19 minutes later, at 4:07 PM.
Sunrise & Sunset with Twilight in December
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 chance that a given day will be muggy in Grytviken is essentially constant during December, remaining around 0% throughout.
Humidity Comfort Levels in December
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 is essentially constant during December, remaining within 0.2 miles per hour of 17.2 miles per hour throughout.
For reference, on August 29, the windiest day of the year, the daily average wind speed is 20.3 miles per hour, while on December 22, the calmest day of the year, the daily average wind speed is 17.0 miles per hour.
The lowest daily average wind speed during December is 17.0 miles per hour on December 22.
Average Wind Speed in December
Wind Direction in December
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 surface water temperature in Grytviken is essentially constant during December, remaining within 1°F of 36°F throughout.
Average Water Temperature in December
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
The growing season in Grytviken typically lasts for 2.6 months (76 days), from around December 31 to around March 18, rarely starting before December 3, or ending after April 21.
The month of December in Grytviken is very likely fully outside of the growing season, with the chance that a given day is in the growing season rapidly increasing from 8% to 50% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in December
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
The average accumulated growing degree days in Grytviken are essentially constant during December, remaining around 0°F throughout.
Growing Degree Days in December
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 in Grytviken is essentially constant during December, remaining within 0.2 kWh of 5.2 kWh throughout.
The highest average daily incident shortwave solar energy during December is 5.4 kWh on December 21.
Average Daily Incident Shortwave Solar Energy in December
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 year round, 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.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.