This report describes the typical weather at the Tromsø Airport (Tromsø, Norway) weather station over the course of an average May. 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 May is characterized by rising daily high temperatures, with daily highs increasing from 42Â°F to 50Â°F over the course of the month, exceeding 59Â°F or dropping below 36Â°F only one day in ten.
Over the course of May, 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 5:10 hours, implying an average day-over-day increase of 10.0 minutes.
The shortest day of the month is May 1 with 18:51 hours of daylight; the longest day is May 31 with 24:00 hours of daylight.
Due to its extreme latitude, Tromsø experiences polar day during summer. During this period of time, the Sun remains continuously above the horizon for a prolonged period of time.
May is in polar day from May 18 onward.
The earliest sunrise is at 1:03am on May 17; the latest sunset is at 12:18am on May 16; the latest sunrise is at 3:19am on May 1; the earliest sunset is at 10:09pm on May 1.
Daylight savings time is observed in 2012 but it neither starts nor ends in May, so the entire month is in daylight time.
The median cloud cover is 87% (mostly cloudy) and does not vary substantially over the course of the month.
On May 16, a representative day, the sky is clear or mostly clear 19% of the time, partly cloudy 19% of the time, and mostly cloudy or overcast 52% of the time.
The average probability that some form of precipitation will be observed in a given day is 68%, with little variation over the course of the month.
Throughout May, the most common forms of precipitation are moderate rain, moderate snow, light rain, and light snow.
Moderate rain is the most severe precipitation observed during 43% of those days with precipitation. It is most likely around May 31, when it is observed during 36% of all days.
Moderate snow is the most severe precipitation observed during 22% of those days with precipitation. It is most likely around May 1, when it is observed during 24% of all days.
Light rain is the most severe precipitation observed during 18% of those days with precipitation. It is most likely around May 23, when it is observed during 14% of all days.
Light snow is the most severe precipitation observed during 13% of those days with precipitation. It is most likely around May 1, when it is observed during 12% of all days.
The likelihood of snow falling is highest around May 1, occurring in 36% of days.
Either snow rarely accumulates at this location in May or snow depth measurements are unavailable or unreliable.
The relative humidity typically ranges from 55% (mildly humid) to 89% (very humid) over the course of a typical May, rarely dropping below 38% (comfortable) and reaching as high as 100% (very humid).
The air is driest around May 17, at which time the relative humidity drops below 64% (mildly humid) three days out of four; it is most humid around May 1, rising above 83% (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 May, the dew point typically varies from 25Â°F (dry) to 39Â°F (dry) and is rarely below 16Â°F (dry) or above 46Â°F (dry).
Over the course of May typical wind speeds vary from 1 mph to 15 mph (calm to moderate breeze), rarely exceeding 25 mph (strong breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around May 31, at which time the average daily maximum wind speed is 15 mph (moderate breeze).
The lowest average wind speed of 8 mph (gentle breeze) occurs around May 10, at which time the average daily maximum wind speed is 14 mph (moderate breeze).