Average Weather in Tromsø Norway
In Tromsø, the summers are short, cool, and mostly cloudy and the winters are long, freezing, windy, and overcast. Over the course of the year, the temperature typically varies from 21°F to 59°F and is rarely below 9°F or above 70°F.
Based on the tourism score, the best time of year to visit Tromsø for warm-weather activities is from mid July to mid August.
The warm season lasts for 2.7 months, from June 13 to September 4, with an average daily high temperature above 53°F. The hottest day of the year is July 23, with an average high of 59°F and low of 48°F.
The cold season lasts for 4.6 months, from November 12 to March 30, with an average daily high temperature below 35°F. The coldest day of the year is January 25, with an average low of 21°F and high of 29°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
In Tromsø, 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 Tromsø begins around April 16 and lasts for 5.3 months, ending around September 27. On May 29, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 44% of the time, and overcast or mostly cloudy 56% of the time.
The cloudier part of the year begins around September 27 and lasts for 6.7 months, ending around April 16. On December 12, the cloudiest day of the year, the sky is overcast or mostly cloudy 80% of the time, and clear, mostly clear, or partly cloudy 20% 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 Tromsø varies throughout the year.
The wetter season lasts 5.3 months, from September 2 to February 11, with a greater than 41% chance of a given day being a wet day. The chance of a wet day peaks at 49% on October 20.
The drier season lasts 6.7 months, from February 11 to September 2. The smallest chance of a wet day is 32% on May 28.
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 Tromsø changes throughout the year.
Rain alone is the most common for 9.0 months, from March 20 to December 19. The highest chance of a day with rain alone is 45% on September 29.
Snow alone is the most common for 3.0 months, from December 19 to March 20. The highest chance of a day with snow alone is 20% on January 28.
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. Tromsø experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Tromsø. The most rain falls during the 31 days centered around October 8, with an average total accumulation of 3.7 inches.
The least rain falls around March 25, with an average total accumulation of 1.5 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. Tromsø experiences significant seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 7.5 months, from September 28 to May 11, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 31, with an average total liquid-equivalent accumulation of 1.7 inches.
The snowless period of the year lasts for 4.6 months, from May 11 to September 28. The least snow falls around July 30, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
Due to its extreme latitude, Tromsø 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 Tromsø during 2020, the Sun is continuously above the horizon for 2.3 months, rising at 1:07 AM on May 17, and not setting again until 12:25 AM on July 26.
In the winter in Tromsø during 2020, the Sun is continuously below the horizon for 1.6 months, setting at 11:56 AM on November 26, and not rising again until 11:50 AM on January 15.
Hours of Daylight and Twilight
Daylight saving time (DST) is observed in Tromsø during 2020, starting in the spring on March 29, lasting 6.9 months, and ending in the fall on October 25.
Sunrise & Sunset with Twilight and Daylight Saving Time
The figure below presents a compact representation of key lunar data for 2020. 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 Tromsø, 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 Tromsø experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 6.1 months, from October 21 to April 24, with average wind speeds of more than 8.1 miles per hour. The windiest day of the year is January 30, with an average hourly wind speed of 11.1 miles per hour.
The calmer time of year lasts for 5.9 months, from April 24 to October 21. The calmest day of the year is July 31, with an average hourly wind speed of 5.1 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Tromsø varies throughout the year.
The wind is most often from the east for 2.6 weeks, from May 12 to May 30, with a peak percentage of 30% on May 20. The wind is most often from the west for 2.8 months, from May 30 to August 23, with a peak percentage of 34% on July 18. The wind is most often from the south for 8.6 months, from August 23 to May 12, with a peak percentage of 47% on January 1.
Tromsø 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 2.4 months, from July 7 to September 20, with an average temperature above 49°F. The day of the year with the warmest water is August 10, with an average temperature of 52°F.
The time of year with cooler water lasts for 4.0 months, from January 9 to May 11, with an average temperature below 41°F. The day of the year with the coolest water is March 23, with an average temperature of 39°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in Tromsø 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 Tromsø for general outdoor tourist activities is from mid July to mid August, with a peak score in the last week of July.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Tromsø for hot-weather activities is from mid to late July.
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 Tromsø typically lasts for 4.3 months (132 days), from around May 15 to around September 24, rarely starting before April 29 or after June 1, and rarely ending before September 3 or after October 13.
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.
Based on growing degree days alone, the first spring blooms in Tromsø should appear around July 2, only rarely appearing before June 16 or after July 23.
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 2.6 months, from May 11 to July 29, with an average daily incident shortwave energy per square meter above 4.2 kWh. The brightest day of the year is June 15, with an average of 5.3 kWh.
The darker period of the year lasts for 5.5 months, from September 29 to March 11, with an average daily incident shortwave energy per square meter below 1.1 kWh. The darkest day of the year is December 10, with an average of 0.0 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Tromsø are 69.649 deg latitude, 18.955 deg longitude, and 46 ft elevation.
The topography within 2 miles of Tromsø contains large variations in elevation, with a maximum elevation change of 1,982 feet and an average elevation above sea level of 209 feet. Within 10 miles contains large variations in elevation (4,003 feet). Within 50 miles also contains extreme variations in elevation (5,981 feet).
The area within 2 miles of Tromsø is covered by trees (36%), artificial surfaces (36%), and water (17%), within 10 miles by trees (22%) and sparse vegetation (22%), and within 50 miles by water (43%) and trees (19%).
This report illustrates the typical weather in Tromsø, 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 are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Tromsø.
For each station, the records are corrected for the elevation difference between that station and Tromsø according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Tromsø is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Tromsø and a given station.
The stations contributing to this reconstruction are: Tromsø Airport, Langnes (97%, 4.0 kilometers, north); Bardufoss Airport (1.4%, 68 kilometers, south); Sørkjosen Airport (1.1%, 79 kilometers, east); and Andøya Andenes Airport (0.6%, 117 kilometers, west).
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.