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December Weather in Longyearbyen Svalbard & Jan Mayen

Daily high temperatures decrease by 3°F, from 19°F to 15°F, rarely falling below -3°F or exceeding 35°F.

Daily low temperatures decrease by 4°F, from 10°F to 6°F, rarely falling below -13°F or exceeding 27°F.

For reference, on July 21, the hottest day of the year, temperatures in Longyearbyen typically range from 41°F to 47°F, while on February 18, the coldest day of the year, they range from 3°F to 14°F.

Average High and Low Temperature in December in Longyearbyen

Average High and Low Temperature in December in LongyearbyenDec1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930303131-20°F-20°F-15°F-15°F-10°F-10°F-5°F-5°F0°F0°F5°F5°F10°F10°F15°F15°F20°F20°F25°F25°F30°F30°F35°F35°F40°F40°FNovJanDec 119°FDec 119°F10°F10°FDec 3115°FDec 3115°F6°F6°FDec 1117°FDec 1117°F8°F8°FDec 2116°FDec 2116°F6°F6°F
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

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 in Longyearbyen

Average Hourly Temperature in December in LongyearbyenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMNovJanfrigidfreezing
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
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

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).

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The month of December in Longyearbyen experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 90% throughout the month.

The clearest day of the month is December 3, with clear, mostly clear, or partly cloudy conditions 12% of the time.

For reference, on January 20, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 92%, while on May 27, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 40%.

Cloud Cover Categories in December in Longyearbyen

Cloud Cover Categories in December in LongyearbyenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%NovJanDec 112%Dec 112%Dec 318%Dec 318%Dec 1111%Dec 1111%Dec 2110%Dec 2110%partly cloudymostly cloudyovercastclearmostly clear
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Longyearbyen, the chance of a wet day over the course of December is gradually increasing, starting the month at 21% and ending it at 24%.

For reference, the year's highest daily chance of a wet day is 27% on September 24, and its lowest chance is 9% on May 28.

Over the course of December in Longyearbyen, the chance of a day with only rain remains an essentially constant 3% throughout, the chance of a day with mixed snow and rain remains an essentially constant 5% throughout, and the chance of a day with only snow increases from 11% to 17%.

Probability of Precipitation in December in Longyearbyen

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

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 Longyearbyen is essentially constant, remaining about 0.4 inches throughout, and rarely exceeding 1.2 inches or falling below -0.0 inches.

Average Monthly Rainfall in December in Longyearbyen

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day snowfall during December in Longyearbyen is increasing, starting the month at 9.2 inches, when it rarely exceeds 16.9 inches or falls below 2.5 inches, and ending the month at 10.4 inches, when it rarely exceeds 17.8 inches or falls below 4.1 inches.

The highest average 31-day accumulation is 10.4 inches on December 30.

Average Monthly Snowfall in December in Longyearbyen

The average snowfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average rainfall.

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 winter in Longyearbyen during 2024, the Sun is continuously below the horizon for 3.7 months, setting at 1:29 PM on October 25, and not rising again until 11:30 AM on February 16. As such, the sun is continuously below the horizon for the entire month of December.

Hours of Daylight and Twilight in December in Longyearbyen

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

Daylight saving time is observed in Longyearbyen during 2024, but it neither starts nor ends during December, so the entire month is in daylight saving time.

Sunrise & Sunset with Twilight in December in Longyearbyen

Sunrise & Sunset with Twilight in December in LongyearbyenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMNovJanSolarMidnightSolarMidnightSolarNoon
The solar day over the course of December. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

Solar Elevation and Azimuth in December in Longyearbyen

Solar Elevation and Azimuth in December in LongyearbyenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMNovJan
northeastsouthwest
Solar elevation and azimuth over the course of December 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for December 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

Moon Rise, Set & Phases in December in Longyearbyen

Moon Rise, Set & Phases in December in LongyearbyenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMNovJanNov 1510:29 PMNov 1510:29 PMDec 1510:02 AMDec 1510:02 AMJan 1311:28 PMJan 1311:28 PM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM
The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.
Dec 2024IlluminationMoonriseMoonsetMoonriseMeridian PassingDistance
1
0%11:45 AMS245,887 mi
2
2%12:45 PMS243,821 mi
3
5%1:47 PMS241,689 mi
4
11%2:49 PMS239,537 mi
5
19%3:48 PMS237,388 mi
6
29%4:44 PMS235,259 mi
7
39%5:36 PMS233,180 mi
8
50%2:21 PMSE10:38 PMWSW-6:25 PMS231,213 mi
9
63%12:54 PME--7:12 PMS229,463 mi
10
74%-2:01 AMWNW11:30 AMENE8:00 PMS228,075 mi
11
84%-6:26 AMNNW8:57 AMNNE8:48 PMS227,219 mi
12
92%9:39 PMS227,061 mi
13
97%10:33 PMS227,725 mi
14
100%11:29 PMS229,256 mi
15
100%--
16
100%12:27 AMS231,592 mi
17
97%1:22 AMS234,561 mi
18
91%2:15 AMS237,910 mi
19
84%3:03 AMS241,348 mi
20
76%3:48 AMS244,584 mi
21
67%-1:35 PMNW9:22 PMENE4:29 AMS247,366 mi
22
50%-12:17 PMW-5:08 AMS249,495 mi
23
48%12:11 AME11:08 AMWSW-5:47 AMS250,838 mi
24
38%3:04 AMSE9:44 AMSW-6:27 AMS251,333 mi
25
29%7:08 AMS250,987 mi
26
20%7:52 AMS249,871 mi
27
13%8:40 AMS248,113 mi
28
7%9:34 AMS245,882 mi
29
3%10:33 AMS243,375 mi
30
0%11:35 AMS240,795 mi
31
0%12:39 PMS238,329 mi

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 Longyearbyen is essentially constant during December, remaining around 0% throughout.

Humidity Comfort Levels in December in Longyearbyen

Humidity Comfort Levels in December in LongyearbyenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%NovJanDec 10%Dec 10%Dec 310%Dec 310%Dec 110%Dec 110%Dec 210%Dec 210%drydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

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 is increasing during December, increasing from 12.0 miles per hour to 13.2 miles per hour over the course of the month.

For reference, on January 2, the windiest day of the year, the daily average wind speed is 13.3 miles per hour, while on June 20, the calmest day of the year, the daily average wind speed is 7.4 miles per hour.

Average Wind Speed in December in Longyearbyen

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The hourly average wind direction in Longyearbyen throughout December is predominantly from the east, with a peak proportion of 49% on December 30.

Wind Direction in December in Longyearbyen

Wind Direction in December in LongyearbyenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%20%80%40%60%60%40%80%20%100%0%NovJaneastnorthsouthwest
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

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 surface water temperature in Longyearbyen is essentially constant during December, remaining around 32°F throughout.

Average Water Temperature in December in Longyearbyen

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

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 13 to around August 29, rarely starting before May 28 or after June 30, and rarely ending before August 9 or after September 16.

The month of December in Longyearbyen is reliably fully outside of the growing season.

Time Spent in Various Temperature Bands and the Growing Season in December in Longyearbyen

Time Spent in Various Temperature Bands and the Growing Season in December in LongyearbyenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%NovJan-0%Dec 16-0%Dec 160%Nov 160%Nov 16frigidfreezingvery cold
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
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

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 Longyearbyen are essentially constant during December, remaining around 9°F throughout.

Growing Degree Days in December in Longyearbyen

Growing Degree Days in December in LongyearbyenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031312°F2°F4°F4°F6°F6°F8°F8°F10°F10°F12°F12°F14°F14°F16°F16°F18°F18°FNovJanDec 19°FDec 19°FDec 319°FDec 319°FDec 119°FDec 119°FDec 219°FDec 219°F
The average growing degree days accumulated over the course of December, with 25th to 75th and 10th to 90th percentile bands.

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 Longyearbyen is essentially constant during December, remaining around 0.0 kWh throughout.

Average Daily Incident Shortwave Solar Energy in December in Longyearbyen

Average Daily Incident Shortwave Solar Energy in December in LongyearbyenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310.0000 kWh0.0000 kWh0.0005 kWh0.0005 kWh0.0010 kWh0.0010 kWh0.0015 kWh0.0015 kWh0.0020 kWh0.0020 kWh0.0025 kWh0.0025 kWh0.0030 kWh0.0030 kWh0.0035 kWh0.0035 kWh0.0040 kWh0.0040 kWh0.0045 kWh0.0045 kWh0.0050 kWh0.0050 kWh0.0055 kWh0.0055 kWh0.0060 kWh0.0060 kWhNovJanDec 10.0 kWhDec 10.0 kWhDec 310.0 kWhDec 310.0 kWhDec 110.0 kWhDec 110.0 kWhDec 210.0 kWhDec 210.0 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

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.

Other Data

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 © OpenStreetMap contributors.

Disclaimer

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.

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