Average Weather in Longyearbyen Svalbard & Jan Mayen
In Longyearbyen, the summers are short, very cold, and dry; the winters are long, frigid, snowy, and windy; and it is overcast year round. Over the course of the year, the temperature typically varies from 3°F to 47°F and is rarely below -19°F or above 53°F.
Based on the tourism score, the best time of year to visit Longyearbyen for warm-weather activities is from mid to late July.
The warm season lasts for 2.5 months, from June 18 to September 3, with an average daily high temperature above 40°F. The hottest day of the year is July 22, with an average high of 47°F and low of 41°F.
The cold season lasts for 5.0 months, from November 23 to April 21, with an average daily high temperature below 20°F. The coldest day of the year is February 18, with an average low of 3°F and high of 14°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
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
Big Sky, Montana, United States (3,629 miles away); Sŭngjibaegam, North Korea (3,749 miles); and Sinegorsk, Russia (3,500 miles) are the far-away foreign places with temperatures most similar to Longyearbyen (view comparison).
In Longyearbyen, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Longyearbyen begins around April 20 and lasts for 5.7 months, ending around October 11. On May 28, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 40% of the time, and overcast or mostly cloudy 60% of the time.
The cloudier part of the year begins around October 11 and lasts for 6.3 months, ending around April 20. On January 20, the cloudiest day of the year, the sky is overcast or mostly cloudy 92% of the time, and clear, mostly clear, or partly cloudy 8% of the time.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Longyearbyen varies throughout the year.
The wetter season lasts 8.9 months, from July 22 to April 18, with a greater than 18% chance of a given day being a wet day. The chance of a wet day peaks at 27% on September 25.
The drier season lasts 3.1 months, from April 18 to July 22. The smallest chance of a wet day is 9% on May 29.
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 Longyearbyen changes throughout the year.
Snow alone is the most common for 7.2 months, from October 13 to May 19. The highest chance of a day with snow alone is 18% on January 5.
Rain alone is the most common for 4.8 months, from May 19 to October 13. The highest chance of a day with rain alone is 24% on September 2.
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. Longyearbyen experiences some seasonal variation in monthly rainfall.
The rainy period of the year lasts for 5.2 months, from June 12 to November 18, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around September 12, with an average total accumulation of 1.4 inches.
The rainless period of the year lasts for 6.8 months, from November 18 to June 12. The least rain falls around April 9, with an average total accumulation of 0.2 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. Longyearbyen experiences significant seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 9.0 months, from September 8 to June 9, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around December 31, with an average total liquid-equivalent accumulation of 1.0 inches.
The snowless period of the year lasts for 3.0 months, from June 9 to September 8. The least snow falls around July 25, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
Due to its extreme latitude, Longyearbyen experiences polar day (also known as the midnight Sun) during the summer and polar night during the winter. These are periods of time in which the sun is continuously above or below the horizon for more than one day. The precise start and end dates of polar day and night vary from year to year and depend on the precise location and elevation of the observer, and the local topography.
In the summer in Longyearbyen during 2021, the Sun is continuously above the horizon for 4.2 months, rising at 1:29 AM on April 18, and not setting again until 12:20 AM on August 25.
In the winter in Longyearbyen during 2021, the Sun is continuously below the horizon for 3.6 months, setting at 12:49 PM on October 26, and not rising again until 11:43 AM on February 15.
Hours of Daylight and Twilight
Daylight saving time (DST) is observed in Longyearbyen during 2021, starting in the spring on March 28, lasting 7.1 months, and ending in the fall on October 31.
Sunrise & Sunset with Twilight and Daylight Saving Time
The figure below presents a compact representation of key lunar data for 2021. 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.
Moon Rise, Set & 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 Longyearbyen, 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
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Longyearbyen experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 6.0 months, from October 19 to April 19, with average wind speeds of more than 10.4 miles per hour. The windiest day of the year is January 2, with an average hourly wind speed of 13.3 miles per hour.
The calmer time of year lasts for 6.0 months, from April 19 to October 19. The calmest day of the year is June 21, with an average hourly wind speed of 7.4 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Longyearbyen is from the east throughout the year.
Longyearbyen 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 1.7 months, from July 12 to September 2, with an average temperature above 38°F. The day of the year with the warmest water is August 6, with an average temperature of 39°F.
The time of year with cooler water lasts for 7.5 months, from October 23 to June 8, with an average temperature below 33°F. The day of the year with the coolest water is February 14, with an average temperature of 32°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in Longyearbyen throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Longyearbyen for general outdoor tourist activities is from mid to late July.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F.
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 Longyearbyen typically lasts for 2.5 months (76 days), from around June 14 to around August 30, rarely starting before May 29 or after July 1, and rarely ending before August 10 or after September 17.
Time Spent in Various Temperature Bands and the Growing Season
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
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.
Growing Degree Days
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 2.0 months, from May 14 to July 14, with an average daily incident shortwave energy per square meter above 4.7 kWh. The brightest day of the year is June 8, with an average of 5.9 kWh.
The darker period of the year lasts for 6.5 months, from September 12 to March 28, with an average daily incident shortwave energy per square meter below 1.2 kWh. The darkest day of the year is January 1, with an average of 0.0 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Longyearbyen are 78.223 deg latitude, 15.647 deg longitude, and 20 ft elevation.
The topography within 2 miles of Longyearbyen contains very significant variations in elevation, with a maximum elevation change of 1,594 feet and an average elevation above sea level of 358 feet. Within 10 miles contains very significant variations in elevation (3,448 feet). Within 50 miles also contains extreme variations in elevation (4,160 feet).
The area within 2 miles of Longyearbyen is covered by snow and glaciers (36%), water (35%), and sparse vegetation (25%), within 10 miles by snow and glaciers (50%) and water (30%), and within 50 miles by snow and glaciers (60%) and water (28%).
This report illustrates the typical weather in Longyearbyen, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There is only a single weather station, Svalbard Airport, Longyear, in our network suitable to be used as a proxy for the historical temperature and dew point records of Longyearbyen.
At a distance of 5 kilometers from Longyearbyen, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.
The station records are corrected for the elevation difference between the station and Longyearbyen according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
Please note that the station records themselves may additionally have been back-filled using other nearby stations or the MERRA-2 reanalysis.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . 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.
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 airports 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.