Average Weather in Duluth Minnesota, United States
In Duluth, the temperature typically varies from 7°F to 78°F over the course of the year, and is rarely below -15°F or above 88°F.
The warm season lasts for 3.4 months, from June 5 to September 16, with an average daily high temperature above 66°F. The hottest day of the year is July 19, with an average high of 78°F and low of 60°F.
The cold season lasts for 3.5 months, from November 26 to March 9, with an average daily high temperature below 34°F. The coldest day of the year is January 20, with an average low of 7°F and high of 22°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
The length of the day in Duluth varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 32 minutes of daylight; the longest day is June 21, with 15 hours, 52 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:13 AM on June 15, and the latest sunrise is 2 hours, 42 minutes later at 7:55 AM on November 4. The earliest sunset is at 4:20 PM on December 10, and the latest sunset is 4 hours, 47 minutes later at 9:06 PM on June 25.
Daylight saving time (DST) is observed in Duluth during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time
In Duluth, 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 Duluth begins around June 8 and lasts for 4.1 months, ending around October 11. On August 1, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 71% of the time, and overcast or mostly cloudy 29% of the time.
The cloudier part of the year begins around October 11 and lasts for 7.9 months, ending around June 8. On January 25, the cloudiest day of the year, the sky is overcast or mostly cloudy 63% of the time, and clear, mostly clear, or partly cloudy 37% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Duluth varies significantly throughout the year.
The wetter season lasts 6.0 months, from April 15 to October 16, with a greater than 24% chance of a given day being a wet day. The chance of a wet day peaks at 41% on June 25.
The drier season lasts 6.0 months, from October 16 to April 15. The smallest chance of a wet day is 7% on February 3.
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 Duluth changes throughout the year.
Rain alone is the most common for 8.7 months, from March 14 to December 3. The highest chance of a day with rain alone is 41% on June 25.
Snow alone is the most common for 3.3 months, from December 3 to March 14. The highest chance of a day with snow alone is 8% on January 1.
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 in the year. Duluth experiences significant seasonal variation in monthly rainfall.
The rainy period of the year lasts for 9.0 months, from March 9 to December 8, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around June 22, with an average total accumulation of 3.9 inches.
The rainless period of the year lasts for 3.0 months, from December 8 to March 9. The least rain falls around January 26, with and average total accumulation of 0.1 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 in the year. Duluth experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 6.3 months, from October 25 to May 3, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around March 8, with an average total liquid-equivalent accumulation of 0.5 inches.
The snowless period of the year lasts for 5.7 months, from May 3 to October 25. The least snow falls around July 17, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
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.
Duluth experiences some seasonal variation in the perceived humidity.
The muggier period of the year lasts for 2.7 months, from June 22 to September 13, during which time the comfort level is muggy, oppressive, or miserable at least 5% of the time. The muggiest day of the year is July 26, with muggy conditions 20% of the time.
The least muggy day of the year is November 28, when muggy conditions are essentially unheard of.
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 Duluth experiences mildly seasonal variation over the course of the year.
The windier part of the year lasts for 7.8 months, from September 19 to May 14, with average wind speeds of more than 5.2 miles per hour. The windiest day of the year is January 15, with an average hourly wind speed of 6.0 miles per hour.
The calmer time of year lasts for 4.2 months, from May 14 to September 19. The calmest day of the year is July 31, with an average hourly wind speed of 4.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Duluth varies throughout the year.
The wind is most often from the north for 1.2 months, from February 23 to March 29, with a peak percentage of 32% on January 15. The wind is most often from the east for 2.5 months, from March 29 to June 13, with a peak percentage of 35% on May 12. The wind is most often from the west for 2.2 months, from June 13 to August 18 and for 5.4 months, from September 13 to February 23, with a peak percentage of 38% on December 13.
Duluth 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 significant seasonal variation over the course of the year.
The time of year with warmer water lasts for 1.9 months, from July 23 to September 21, with an average temperature above 57°F. The day of the year with the warmest water is August 19, with an average temperature of 62°F.
The time of year with cooler water lasts for 5.9 months, from December 4 to May 31, with an average temperature below 40°F. The day of the year with the coolest water is March 3, with an average temperature of 34°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 very significant seasonal variation over the course of the year.
The brighter period of the year lasts for 3.6 months, from May 4 to August 23, with an average daily incident shortwave energy per square meter above 5.7 kWh. The brightest day of the year is July 10, with an average of 6.8 kWh.
The darker period of the year lasts for 3.5 months, from October 27 to February 12, with an average daily incident shortwave energy per square meter below 2.4 kWh. The darkest day of the year is December 16, with an average of 1.2 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Duluth are 46.783 deg latitude, -92.107 deg longitude, and 689 ft elevation (map ).
The topography within 2 miles of Duluth contains significant variations in elevation, with a maximum elevation change of 764 feet, and an average elevation above sea level of 848 feet. Within 10 miles contains very significant variations in elevation (899 feet). Within 50 miles also contains very significant variations in elevation (1,368 feet).
The area within 2 miles of Duluth is covered by water (38%), artificial surfaces (36%), and trees (14%), within 10 miles by trees (48%) and water (34%), and within 50 miles by trees (74%) and water (14%).
This report illustrates the typical weather in Duluth, 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 Duluth.
For each station, the records are corrected for the elevation difference between that station and Duluth 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 Duluth is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Duluth and a given station.
The stations contributing to this reconstruction are: Duluth International Airport (17%, 8 kilometers, northwest), Sky Harbor Airport (76%, 8 kilometers, southeast), and Two Harbors (7%, 40 kilometers, northeast).
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 .