Welcome to this Longyearbyen climate guide! As the capital of Svalbard, Longyearbyen experiences a tundra climate that is influenced by various geographical factors, making the climate of Longyearbyen milder than other regions at the same latitude. In this article, we will examine these factors shaping Longyearbyen’s climate, discuss the typical weather you can expect, delve into seasonal variations, discuss the aurora (Northern Light) season, and explore extreme conditions. We will also touch on how Longyearbyen’s climate is rapidly changing as one of the fastest warming places on earth.
The Climate of Longyearbyen: A Tundra Climate
Situated at an extremely high latitude of 78 degrees north, Longyearbyen is surrounded by the waters of the Greenland Sea, Barentsz Sea, and Arctic Ocean. Despite its extreme northern position—about 900 km north of the Norwegian mainland—the warm Gulf Stream has a moderating effect, making Longyearbyen’s climate substantially milder compared to other areas at similar latitudes (as an example, see here the climate of Cambridge Bay in the Canadian Arctic. This region is much further south, yet much colder than Longyearbyen).
Yet, as a consequence of its geographical factors, Longyearbyen experiences a long polar night and midnight sun period, both lasting about 4 months. This leads to long, cold winters and brief, cool summers. The yearly average temperature hovers around -3.8°C. Even in its warmest month, the average temperature does normally not exceed 10.0°C, leading to its classification under the Köppen climate system as a tundra climate (ET).
The town’s climate is also strongly influenced by regional features. Fjords, valleys, and mountains in the vicinity create microclimates and variable weather patterns, further enriching the complexity of Longyearbyen’s tundra climate.
Typical Weather in Longyearbyen, Svalbard
Longyearbyen’s arctic climate means frost is possible any time of year, though rare from late June to late August. The first signs of winter, including frost, ice days, and snowfall, generally emerge in September. By October, sub-zero temperatures dominate, with winters occasionally witnessing temperatures surpassing freezing. July is the warmest month with a daily maximum slightly above 9°C, while February and March plunge into the coldest extremes, showcasing daily maximums around -8°C to -9°C, and chilling monthly minimums below -25°C.
The annual precipitation totals to 217mm, a number that is increasing due to climate change. September receives the most precipitation, slightly above 25mm, with winter months like November and January not far behind. While rain is predominant at sea level from mid June to mid August, snow can still give the surrounding mountains a white dusting. The transition to snow starts in September and a permanent snow cover solidifies by October or November. Yet, increased rain events in recent years have disrupted this pattern. Winter precipitation predominantly falls as snow, but occasional rain events - that can lead to freezing rain, creating perilously icy conditions – have increased in frequency over the years.
Seasonal variation in Longyearbyen: What weather to expect throughout the year
Distinguishing Longyearbyen’s climate into different seasons is not as straightforward as in other parts of the world. The transition between summer and winter occurs rapidly, largely influenced by the extended periods of the midnight sun and polar night. Nevertheless, the climate can be divided into four main seasons of various lengths. The winter season can be further divided into two distinct phases: the ‘dark winter’ and the ‘light winter’.
Longyearbyen winter climate (October to April): how cold does it get?
Dark winter in Longyearbyen: falling temperatures
From October onwards, frost becomes a regular occurrence, even though temperatures occasionally rise above 0°C. Throughout the winter, short spells of temperatures above freezing can occur, sometimes even accompanied by rain. However, as the ‘dark winter’ phase sets in, from late October to late January, such positive temperatures become increasingly infrequent. This phase is characterized by perpetual darkness; the sun remains hidden below the horizon, starting around the 27th of October. This is also the time when the captivating Aurora Borealis, commonly known as the Northern Lights, can be admired – more on that in a later section.
Dark, snowy and cold – this is what Longyearbyen might look like in the dark winter period. Photo taken during daytime, November 27th, 2018.
Light winter in Longyearbyen: the coldest time of year
February stands as a transitional month. The town gradually welcomes the light back, but ironically, it also marks the onset of the coldest period: the ‘light winter’. Spanning from February to April, this phase, despite its luminosity, brings the chilliest temperatures of the year. Although Longyearbyen’s lows aren’t as extreme as other locales at similar latitudes, the mercury can occasionally plummet below -20°C. On average, daily highs hover just above -10°C. Compounding the cold, strong winds regularly occur in and around Longyearbyen during winter. This leads to low wind chills, making perceived temperatures drop by an additional 10°C or more, which substantially heightens the risk of frostbite.
During the light winter, the snow cover reaches its peak depth, generally measuring several decimeters – although snow cover strongly varies from one location to another due to redistribution of the snowpack influenced by wind and the topography. With the returning daylight and this abundant snow cover, it becomes an ideal period for snowmobile adventures and skiing excursions.
Longyearbyen, Svalbard during the light winter. This is the time for snowmobile trips. Photo taken on March 13th, 2022.
Longyearbyen spring climate (Late April to May): start of midnight sun and rising temperatures
The brief spring season in Longyearbyen starts in late April, with the midnight sun beginning its constant presence around the 20th. As the days progress, the temperatures show an upward trend. Although May’s average temperatures predominantly linger below freezing, the latter half of the month sees daily highs regularly surpassing 0°C. It’s during this period that the snow cover begins to thin out and retreat. Together with June, spring represents the year’s driest period. Any precipitation that does manifest in spring typically still falls as snow.
This is what Longyearbyen may look like in the summer. Photo taken August 13th, 2018.
Longyearbyen summer climate (June to mid-August):
June experiences a warm shift, with frost being quite rare. While there might be a day or two of frost, especially in the initial days of the month, it’s an exception rather than the rule. Throughout June, temperatures predominantly remain above the freezing point. In this relatively dry month, the form of precipitation transitions from snow to rain at lower altitudes. While the snow clears from the valley, remnants can still be found in the mountains.
As we move into July, the warmest month of the season, even those lingering snow patches in the mountains begin to melt, with daily highs occasionally exceeding 10°C. The highest average temperature of the year typically occurs in July, sometimes in early August, and tends to be just above 15°C. However, in recent years, there have been days with highs surpassing 20°C. Summer in Longyearbyen also sees episodes of high relative humidity, leading to the presence of low clouds, fog, and drizzle. Precipitation tends to increase as the season transitions towards autumn. Generally, summer is marked by calm winds.
Longyearbyen autumn climate (mid-August to September): first frost and the end of midnight sun
In August, the temperature gradually starts dropping again, as the sun stands at a gradually lower angle on the horizon. Cloudy weather occurs frequently in late august and September, while precipitation is common. The sun sets for the first time again around the 25th of August, after which the days rapidly get shorter. However, even until well in September, the nights do not get fully dark as the sun is only a few degrees below the horizon at maximum, which means there is some twilight during the night.
The first frost generally occurs in late August or September. It is during this time that the precipitation regularly leaves a white dusting over the mountains again. The first snow cover of the year in the valley typically occurs in September, but this snow cover is generally not permanent. As autumn goes on, the winds pick up compared to the summer.
Aurora season in Longyearbyen – daytime auroras
In Longyearbyen, the best months to observe auroras are generally from October to early March. During much of this period, the polar night provides the necessary darkness for optimal viewing.
Contrary to what one might expect, the high northern location of Longyearbyen is not the most ideal place to view the auroras. In fact Longyearbyen’s extreme northern location places it slightly north of the main aurora activity zone. Nevertheless, Longyearbyen has the advantage that it stays dark 24 hours a day during the polar night. For this reason, Longyearbyen is one of the few places in the world where one can observe “daytime auroras”.
Extreme Weather in Longyearbyen
Weather in Longyearbyen can change quickly. A calm, sunny morning can turn into a strong blizzard with zero visibility by the afternoon. Winds in the area can be strong, but they can change a lot in strength and direction over short distances due to local wind channelling effects by the mountains and valleys. So, a calm day in the Longyearbyen Valley doesn’t always mean it’s calm outside of the town. Here you can find an example of a blizzard in Longyearbyen, or check the video below.
Longyearbyen gets very cold because of its Arctic climate, however, by far not as cold as other regions at similar latitudes. The coldest day ever recorded was on March 4, 1986, with a temperature of -46.3°C. In recent years, it has become extremely rare for the temperature to go below -30°C. Even though Longyearbyen is milder compared to other places at the same latitude, the cold can feel worse because of the wind and humidity. The wind chill is therefore often much colder than the actual air temperature. This is something to remember if you’re going out in Longyearbyen or anywhere in Svalbard. On average, the coldest temperature in a year is -28.6°C, and the warmest is 15.4°C. The hottest day on record was on July 25, 2020, when the mercury reached 21.7°C.
As for rain and snow, there were only two months without any precipitation: May 1923 and December 2019. The month with the most precipitation was January 2010, with 83.1 mm. The day with the most rain occurred in August 1981, with 43.2 mm.
Climate change in Longyearbyen & Svalbard
Longyearbyen, and Svalbard as a whole, is at the forefront of climate change, warming at a pace among the fastest on Earth. This accelerated warming is due in part to the warm Gulf Stream’s increased influence in the Greenland and Barents Seas and a shift in weather patterns, with low-pressure systems more frequently passing Svalbard on its western side. This change causes more southerly winds on Svalbard, placing Svalbard on the warmer side of these systems.
The average winter temperature at Longyearbyen Airport, Svalbard. Note: the year 2020 on the x-axis means the winter season of 2020 (so December 2019-February 2020). Winters in Longyearbyen are warming rapidly.
As a result, Longyearbyen is witnessing a rapid increase in temperatures and precipitation. The fjords in Longyearbyen’s proximity, such as Adventfjorden and larger parts of Isfjorden that historically froze, now rarely do so, even during the peak of winter, further enhancing local air temperatures.
The town is experiencing more frequent rain events in the late fall and winter, disrupting the usual snowfall patterns. When it does snow however, more snow gets dumped than during snow events in the past. The melt and refreeze of snow, more significant rain-on-snow events and heavier snowfalls altogether lead to higher avalanche risks. Permafrost, once a permanent frozen layer beneath the surface, is beginning to thaw, increasing the likelihood of mudslides and landslides, reshaping the very ground Longyearbyen is built on.
Temperatures are rising year-round, with winters seeing the most rapid warming – about 8°C since 1970! Unprecedented temperature highs have been recorded, such as four consecutive days above 20°C in July 2020 — a clear departure from historical norms. The future promises a continuation of these trends: a warmer Longyearbyen with melting glaciers, diminishing sea ice, and an increase in precipitation, more of which may fall as rain. The implications are profound, increasing the risk of mudslides and avalanches and changing the habitat of many species, altering the Arctic landscape that Longyearbyen calls home.