Average Weather in Alta Norway
In Alta, the summers are short, cool, and mostly cloudy and the winters are long, freezing, snowy, windy, and overcast. Over the course of the year, the temperature typically varies from 13°F to 62°F and is rarely below -4°F or above 74°F.
The warm season lasts for 2.7 months, from June 13 to September 4, with an average daily high temperature above 54°F. The hottest day of the year is July 24, with an average high of 62°F and low of 51°F.
The cold season lasts for 4.3 months, from November 13 to March 21, with an average daily high temperature below 32°F. The coldest day of the year is January 25, with an average low of 13°F and high of 24°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
In Alta, 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 Alta begins around April 12 and lasts for 5.3 months, ending around September 20. On June 7, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 40% of the time, and overcast or mostly cloudy 60% of the time.
The cloudier part of the year begins around September 20 and lasts for 6.7 months, ending around April 12. On January 3, the cloudiest day of the year, the sky is overcast or mostly cloudy 82% of the time, and clear, mostly clear, or partly cloudy 18% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Alta varies throughout the year.
The wetter season lasts 5.3 months, from May 31 to November 8, with a greater than 31% chance of a given day being a wet day. The chance of a wet day peaks at 39% on October 21.
The drier season lasts 6.7 months, from November 8 to May 31. The smallest chance of a wet day is 22% on March 9.
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 Alta changes throughout the year.
Rain alone is the most common for 7.1 months, from April 7 to November 8. The highest chance of a day with rain alone is 37% on June 20.
Snow alone is the most common for 4.9 months, from November 8 to April 7. The highest chance of a day with snow alone is 19% on January 19.
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. Alta experiences significant seasonal variation in monthly rainfall.
The rainy period of the year lasts for 8.0 months, from March 31 to December 1, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around July 13, with an average total accumulation of 2.7 inches.
The rainless period of the year lasts for 4.0 months, from December 1 to March 31. The least rain falls around February 25, with an average total accumulation of 0.3 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. Alta experiences significant seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 7.1 months, from October 3 to May 7, 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 28, with an average total liquid-equivalent accumulation of 1.0 inches.
The snowless period of the year lasts for 4.9 months, from May 7 to October 3. The least snow falls around July 23, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
Due to its extreme latitude, Alta 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 Alta during 2017, the Sun is continuously above the horizon for 2.4 months, rising at 12:47 AM on May 16, and not setting again until 12:00 AM on July 28.
In the winter in Alta during 2017, the Sun is continuously below the horizon for 1.7 months, setting at 11:26 AM on November 25, and not rising again until 11:33 AM on January 16.
Hours of Daylight and Twilight
Daylight saving time (DST) is observed in Alta during 2017, starting in the spring on March 26, lasting 7.1 months, and ending in the fall on October 29.
Sunrise & Sunset with Twilight and Daylight Saving Time
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 Alta, 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
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 Alta experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 5.7 months, from October 31 to April 20, with average wind speeds of more than 5.7 miles per hour. The windiest day of the year is January 28, with an average hourly wind speed of 7.3 miles per hour.
The calmer time of year lasts for 6.4 months, from April 20 to October 31. The calmest day of the year is August 13, with an average hourly wind speed of 4.2 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Alta varies throughout the year.
The wind is most often from the west for 1.5 months, from May 22 to July 7, with a peak percentage of 32% on June 4. The wind is most often from the south for 10 months, from July 7 to May 22, with a peak percentage of 48% on January 1.
Alta 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 6 to September 17, with an average temperature above 48°F. The day of the year with the warmest water is August 7, with an average temperature of 51°F.
The time of year with cooler water lasts for 4.6 months, from December 31 to May 18, with an average temperature below 40°F. The day of the year with the coolest water is March 30, with an average temperature of 38°F.
Average Water Temperature
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 10 to July 30, with an average daily incident shortwave energy per square meter above 4.2 kWh. The brightest day of the year is June 17, with an average of 5.2 kWh.
The darker period of the year lasts for 5.4 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 12, with an average of 0.0 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Alta are 69.969 deg latitude, 23.272 deg longitude, and 3 ft elevation.
The topography within 2 miles of Alta contains significant variations in elevation, with a maximum elevation change of 669 feet and an average elevation above sea level of 71 feet. Within 10 miles contains significant variations in elevation (3,281 feet). Within 50 miles also contains extreme variations in elevation (4,373 feet).
The area within 2 miles of Alta is covered by artificial surfaces (39%), cropland (24%), trees (17%), and water (14%), within 10 miles by trees (40%) and sparse vegetation (22%), and within 50 miles by sparse vegetation (39%) and water (18%).
This report illustrates the typical weather in Alta, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Alta.
For each station, the records are corrected for the elevation difference between that station and Alta 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 Alta is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Alta and a given station.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , 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 aiports 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.