This report describes the typical weather at the Svalbard Airport (Longyearbyen, Svalbard and Jan Mayen) weather station over the course of an average year. It is based on the historical records from 1985 to 2012. Earlier records are either unavailable or unreliable.
Longyearbyen has a polar tundra climate. The area within 25 mi of this station is covered by tundra (60%) and oceans and seas (40%).
Over the course of a year, the temperature typically varies from 2°F to 48°F and is rarely below -18°F or above 54°F.
The warm season lasts from June 15 to September 4 with an average daily high temperature above 41°F. The hottest day of the year is July 23, with an average high of 48°F and low of 42°F.
The cold season lasts from December 3 to April 19 with an average daily high temperature below 20°F. The coldest day of the year is February 24, with an average low of 2°F and high of 13°F.
The length of the day varies significantly over the course of the year. The shortest day is December 21 with 0:00 hours of daylight; the longest day is June 20 with 24:00 hours of daylight.
Due to its extreme latitude, Longyearbyen experiences polar day (also known as the midnight Sun) during summer and polar night during winter. 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 summer, the Sun is continuously above the horizon for 126 days, from April 19 to August 23.
In winter, the Sun is continuously below the horizon for 112 days, from October 26 to February 15.
Daylight savings time (DST) is observed in this location during 2012, starting in the spring on March 25 and ending in the fall on October 28.
The median cloud cover ranges from 66% (partly cloudy) to 90% (mostly cloudy). The sky is cloudiest on August 27 and clearest on January 8. The clearer part of the year begins around November 15. The cloudier part of the year begins around May 2.
On January 8, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 49% of the time, and overcast or mostly cloudy 42% of the time.
On August 27, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 84% of the time, and clear or mostly clear 10% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around November 6, occurring in 74% of days. Precipitation is least likely around June 9, occurring in 53% of days.
Over the entire year, the most common forms of precipitation are light snow, moderate snow, moderate rain, and light rain.
Light snow is the most severe precipitation observed during 41% of those days with precipitation. It is most likely around November 18, when it is observed during 40% of all days.
Moderate snow is the most severe precipitation observed during 34% of those days with precipitation. It is most likely around November 11, when it is observed during 32% of all days.
Moderate rain is the most severe precipitation observed during 11% of those days with precipitation. It is most likely around August 5, when it is observed during 23% of all days.
Light rain is the most severe precipitation observed during 10% of those days with precipitation. It is most likely around July 19, when it is observed during 21% of all days.
During the warm season, which lasts from June 15 to September 4, there is a 57% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of moderate rain (35% of days with precipitation have at worst moderate rain), light rain (33%), light snow (12%), and drizzle (11%).
During the cold season, which lasts from December 3 to April 19, there is a 65% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light snow (53% of days with precipitation have at worst light snow) and moderate snow (44%).
The likelihood of snow falling is highest around November 25, occurring in 72% of days. The season in which it is relatively likely for snow to fall spans from September 3 to June 18.
During peak snow season, accumulation at this location on a given day is just less likely than not. The chances of there being snow on the ground are highest around March 14, occurring 35% of the time. The season in which snow is relatively likely to be on the ground spans from September 25 to May 31.
The snow is typically at its deepest on April 7, with a median depth of 12.0"; the depth exceeds 18.4" only one year out of ten.
The relative humidity typically ranges from 61% (mildly humid) to 90% (very humid) over the course of the year, rarely dropping below 47% (comfortable) and reaching as high as 100% (very humid).
The air is driest around July 1, at which time the relative humidity drops below 69% (mildly humid) three days out of four; it is most humid around August 3, exceeding 85% (humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a year, the dew point typically varies from -5°F (dry) to 41°F (dry) and is rarely below -24°F (dry) or above 45°F (dry).
Over the course of the year typical wind speeds vary from 1 mph to 22 mph (light air to fresh breeze), rarely exceeding 35 mph (high wind).
The highest average wind speed of 14 mph (moderate breeze) occurs around January 1, at which time the average daily maximum wind speed is 22 mph (fresh breeze).
The lowest average wind speed of 8 mph (gentle breeze) occurs around June 3, at which time the average daily maximum wind speed is 14 mph (moderate breeze).