Climate and Average Weather Year Round in Grytviken South Georgia & South Sandwich Islands

In Grytviken, the summers are short and very cold; the winters are long, freezing, and snowy; and it is extremely windy and overcast year round. 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.

The warm season lasts for 3.0 months, from December 29 to March 28, with an average daily high temperature above 38°F. The hottest month of the year in Grytviken is February, with an average high of 40°F and low of 36°F.

The cold season lasts for 4.2 months, from June 3 to October 11, with an average daily high temperature below 33°F. The coldest month of the year in Grytviken is August, with an average low of 26°F and high of 31°F.

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 September 30 and lasts for 6.1 months, ending around April 2.

The clearest month of the year in Grytviken is December, during which on average the sky is clear, mostly clear, or partly cloudy 36% of the time.

The cloudier part of the year begins around April 2 and lasts for 5.9 months, ending around September 30.

The cloudiest month of the year in Grytviken is July, during which on average the sky is overcast or mostly cloudy 78% of the time.

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 15 to May 13, with a greater than 33% chance of a given day being a wet day. The month with the most wet days in Grytviken is February, with an average of 12.2 days with at least 0.04 inches of precipitation.

The drier season lasts 6.1 months, from May 13 to November 15. The month with the fewest wet days in Grytviken is October, with an average of 7.7 days with at least 0.04 inches of precipitation.

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 21 to August 27 and from September 20 to July 25. The month with the most days of rain alone in Grytviken is February, with an average of 12.2 days.

Mixed snow and rain is the most common for 1.5 months, from July 25 to August 21 and from September 2 to September 20. The month with the most days of mixed snow and rain in Grytviken is August, with an average of 2.8 days.

Snow alone is the most common for 6.0 days, from August 27 to September 2. The month with the most days of snow alone in Grytviken is August, with an average of 2.5 days.

Rainfall

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 month with the most rain in Grytviken is February, with an average rainfall of 2.8 inches.

The month with the least rain in Grytviken is August, with an average rainfall of 0.7 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Grytviken experiences significant seasonal variation in monthly snowfall.

The snowy period of the year lasts for 7.3 months, from April 21 to November 29, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Grytviken is September, with an average snowfall of 6.0 inches.

The snowless period of the year lasts for 4.7 months, from November 29 to April 21. The least snow falls around February 8, with an average total accumulation of 0.0 inches.

The length of the day in Grytviken varies extremely over the course of the year. In 2024, the shortest day is June 20, with 7 hours, 19 minutes of daylight; the longest day is December 21, with 17 hours, 13 minutes of daylight.

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 24. The earliest sunset is at 4:06 PM on June 16, 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 2024.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

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.

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 significant seasonal variation over the course of the year.

The windier part of the year lasts for 4.7 months, from June 12 to November 4, with average wind speeds of more than 18.7 miles per hour. The windiest month of the year in Grytviken is August, with an average hourly wind speed of 19.9 miles per hour.

The calmer time of year lasts for 7.3 months, from November 4 to June 12. The calmest month of the year in Grytviken is December, with an average hourly wind speed of 17.2 miles per hour.

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 3.1 months, from January 10 to April 14, with an average temperature above 37°F. The month of the year in Grytviken with the warmest water is February, with an average temperature of 38°F.

The time of year with cooler water lasts for 4.1 months, from June 30 to November 3, with an average temperature below 34°F. The month of the year in Grytviken with the coolest water is September, with an average temperature of 32°F.

To characterize how pleasant the weather is in Grytviken throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

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 30 to around March 17, rarely starting before December 2, or ending after April 20.

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.

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 10 to January 29, with an average daily incident shortwave energy per square meter above 4.4 kWh. The brightest month of the year in Grytviken is December, with an average of 5.3 kWh.

The darker period of the year lasts for 4.4 months, from April 13 to August 26, with an average daily incident shortwave energy per square meter below 1.4 kWh. The darkest month of the year in Grytviken is June, with an average of 0.4 kWh.

For the purposes of this report, the geographical coordinates of Grytviken are -54.281 deg latitude, -36.509 deg longitude, and 13 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%).