Climate in South Shetland Islands (Antarctica)

The South Shetland Islands have a polar climate, with average temperatures around -5/-6 °C (21/23 °F) in winter, from June to August, and 0.5/2 °C (33/35.5 °F) in summer, from December in March. Wind, cloudy skies, fog, humidity, rain and snow are other typical characteristics of the climate of these islands.
The archipelago is located north of the Antarctic Peninsula, between 61 and 63 degrees south latitude, in the area swept by the westerly winds that blow around Antarctica, often with storm intensity, and bring conditions of bad weather. Instead, icy winds from the continent can arrive from the south, bringing very cold but drier weather, especially in winter.
Since the summer is cold, the islands are almost completely covered by ice even at low altitudes, however, this is the least cold area of Antarctica, and the one with the greatest biodiversity. These islands are even milder than the South Orkneys, which despite being further north, receive the cold currents along with the icebergs of the Weddell Sea.
About 850 kilometers (530 miles) to the northwest, across the Drake Passage, lies the southern tip of Chile and Argentina. Due to the relatively mild climate and thr proximity to South America, the South Shetlands are the area of Antarctica with the greatest concentration of research stations.



The archipelago is made up of around ten main islands, plus several smaller islands. The largest is the King George Island (called Isla 25 de Mayo by the Argentines and Vaterloo by the Russians), followed by Livingston (called Smolensk by the Russians), the first to be discovered, in 1819. Other islands are Elephant, Deception, Penguin, Bridgeman, Aitcho, Greenwich, Half Moon, and Smith.
On King George Island there is a civil settlement, the Chilean Villa Las Estrellas, the only one of its kind together with Esperanza Base, located 165 km (100 mi) further south, on the Antarctic Peninsula, and belonging to Argentina.
The island also hosts an airport, called Teniente Rodolfo Marsh Martin, which serves the Chilean Frei base and the Villa Las Estrellas village, but also receives chartered flights for tourists from the city of Punta Arenas, Chile. However, most tourists arrive by ship, via the Drake Passage, whose waters are often rough.
In the interio of the islands there are mountains and volcanoes, obviously covered in snow all year round. The highest peak is Mount Foster, 2,025 meters (7,234 ft) high and located on Smith Island.
The horseshoe shape of Deception Island is due to the explosion of a volcano thousands of years ago, which left an underwater caldera. The volcano is still active, and has recorded twenty eruptions in the last 200 years.



As mentioned, the average temperatures in the South Shetlands are not that low, however, in summer they remain close to the freezing point, slightly exceeding this value, also due to the influence of the sea, which from April to November partially freezes, and remains cold even in summer.
During cold waves, the temperature can drop below -20 °C (-4 °F) from May to October. The coldest records, generally recorded in July and August, are around -27/-30 °C (-16/-22 °F).
On the other hand, when mild currents prevail, temperatures can slightly exceed freezing even in winter, while in summer they can reach 7/8 °C (45/46 °F), and occasionally 12/13 °C (54/55 °F).

Here are the average temperatures recorded in the Argentine Carlini base (formerly Jubany), located on King George Island.

Precipitation in South Shetland is frequent, even though it is not abundant. On the coasts it ranges from 500 to 700 mm (20 to 27.5 in) per year, with a maximum on the coasts facing north-west, which more easily receive the humid winds that circulate on the oceans around Antarctica. At the Carlini base there are 180 days with snow or sleet per year, with a minimum of 8 days in February and a maximum of 19 days in October.
However, it can also rain, more easily in summer, but sometimes even in winter.
Here is the average precipitation at the Carlini base, which is located on the southern side.

There is very little sunshine in the South Shetlands. Cloudy or overcast days are normal all year round. Days with clear skies are very rare. With less than 600 hours of sunshine a year, we are probably in the least sunny area in the world, together with the South Orkneys, which are further north-east.

Since the South Shetland Islands are north of the polar circle, they experience neither the polar night in winter nor the midnight sun in summer. However, in winter the days are short, and in June there are just over 5 hours of sunlight per day.
On the other hand, for a few weeks around the summer solstice there are white nights, in which it is not completely dark even at midnight. For example, at the Carlini base, the white nights occur from November 5th to February 6th.

When to go

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The best time to visit the South Shetland Islands is summer, from December to February, being the one with the highest temperatures and the longest days. However, rain, wind, snow and strong winds often occur during this period too.