This report describes the typical weather at the Tromsø Airport (Tromsø, Norway) weather station over the course of an average January. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Tromsø has a humid subarctic continental climate with cool summers and no dry season. The area within 25 mi of this station is covered by tundra (47%), oceans and seas (36%), and forests (14%).
The month of January is characterized by essentially constant daily high temperatures, with daily highs around 30°F throughout the month, exceeding 40°F or dropping below 18°F only one day in ten.
Over the course of January, the length of the day is very rapidly increasing. From the start to the end of the month, the length of the day increases by 4:53 hours, implying an average day-over-day increase of 9.4 minutes.
The shortest day of the month is January 1 with 0:00 hours of daylight; the longest day is January 31 with 4:53 hours of daylight.
Due to its extreme latitude, Tromsø experiences polar night during winter. During this period of time, the Sun remains continuously below the horizon for a prolonged period of time.
January begins in polar night, which lasts until January 16.
The earliest sunrise is at 9:32am on January 31; the latest sunset is at 2:24pm on January 31; the latest sunrise is at 11:32am on January 16; the earliest sunset is at 12:17pm on January 16.
Daylight savings time is observed in 2012 but it neither starts nor ends in January, so the entire month is in standard time.
The median cloud cover is 81% (mostly cloudy) and does not vary substantially over the course of the month.
On January 16, a representative day, the sky is clear or mostly clear 19% of the time, partly cloudy 20% of the time, and mostly cloudy or overcast 43% of the time.
The average probability that some form of precipitation will be observed in a given day is 73%, with little variation over the course of the month.
Throughout January, the most common forms of precipitation are moderate snow and light snow.
Moderate snow is the most severe precipitation observed during 67% of those days with precipitation. It is most likely around January 17, when it is observed during 50% of all days.
Light snow is the most severe precipitation observed during 20% of those days with precipitation. It is most likely around January 29, when it is observed during 15% of all days.
The likelihood of snow falling is highest around January 30, occurring in 66% of days.
Accumulation at this location in January is very unlikely. The chances of there being snow on the ground are highest around January 29, occurring 6% of the time.
The snow is typically at its deepest on January 31, with a median depth of 13.1"; the depth exceeds 20.3" only one year out of ten.
The relative humidity typically ranges from 64% (mildly humid) to 92% (very humid) over the course of a typical January, rarely dropping below 49% (comfortable) and reaching as high as 100% (very humid).
The air is driest around January 11, at which time the relative humidity drops below 73% (humid) three days out of four; it is most humid around January 17, rising above 90% (very 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 typical January, the dew point typically varies from 13°F (dry) to 26°F (dry) and is rarely below 2°F (dry) or above 34°F (dry).
Over the course of January typical wind speeds vary from 2 mph to 20 mph (light air to fresh breeze), rarely exceeding 31 mph (high wind).
The highest average wind speed of 12 mph (gentle breeze) occurs around January 24, at which time the average daily maximum wind speed is 20 mph (fresh breeze).
The lowest average wind speed of 11 mph (gentle breeze) occurs around January 3, at which time the average daily maximum wind speed is 19 mph (fresh breeze).