Average Weather in Polson Montana, United States
In Polson, the summers are short, warm, and mostly clear and the winters are freezing and mostly cloudy. Over the course of the year, the temperature typically varies from 19°F to 85°F and is rarely below 2°F or above 93°F.
Based on the tourism score, the best time of year to visit Polson for warm-weather activities is from early July to mid August.
The warm season lasts for 2.8 months, from June 16 to September 8, with an average daily high temperature above 74°F. The hottest day of the year is July 30, with an average high of 85°F and low of 56°F.
The cold season lasts for 3.5 months, from November 13 to February 26, with an average daily high temperature below 41°F. The coldest day of the year is December 31, with an average low of 19°F and high of 30°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 Polson, 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 Polson begins around June 12 and lasts for 3.9 months, ending around October 9. On July 25, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 78% of the time, and overcast or mostly cloudy 22% of the time.
The cloudier part of the year begins around October 9 and lasts for 8.1 months, ending around June 12. On January 10, the cloudiest day of the year, the sky is overcast or mostly cloudy 72% of the time, and clear, mostly clear, or partly cloudy 28% 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 Polson varies throughout the year.
The wetter season lasts 8.3 months, from October 21 to June 30, with a greater than 25% chance of a given day being a wet day. The chance of a wet day peaks at 37% on June 3.
The drier season lasts 3.7 months, from June 30 to October 21. The smallest chance of a wet day is 13% on July 25.
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 Polson changes throughout the year.
Rain alone is the most common for 11 months, from January 13 to December 15. The highest chance of a day with rain alone is 37% on June 3.
Snow alone is the most common for 4.1 weeks, from December 15 to January 13. The highest chance of a day with snow alone is 14% on December 24.
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. Polson experiences some seasonal variation in monthly rainfall.
Rain falls throughout the year in Polson. The most rain falls during the 31 days centered around June 2, with an average total accumulation of 2.7 inches.
The least rain falls around August 3, with an average total accumulation of 0.8 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. Polson experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 5.0 months, from October 28 to March 27, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around December 30, with an average total liquid-equivalent accumulation of 0.8 inches.
The snowless period of the year lasts for 7.0 months, from March 27 to October 28. The least snow falls around July 17, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Polson varies extremely over the course of the year. In 2020, the shortest day is December 21, with 8 hours, 25 minutes of daylight; the longest day is June 20, with 16 hours, 0 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:37 AM on June 15, and the latest sunrise is 2 hours, 47 minutes later at 8:25 AM on December 31. The earliest sunset is at 4:44 PM on December 10, and the latest sunset is 4 hours, 54 minutes later at 9:38 PM on June 25.
Daylight saving time (DST) is observed in Polson during 2020, starting in the spring on March 8, lasting 7.8 months, and ending in the fall on November 1.
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 Polson, 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 Polson does not vary significantly over the course of the year, remaining within 0.4 miles per hour of 4.7 miles per hour throughout.
Average Wind Speed
The predominant average hourly wind direction in Polson varies throughout the year.
The wind is most often from the west for 8.3 months, from March 1 to November 9, with a peak percentage of 61% on June 21. The wind is most often from the south for 3.7 months, from November 9 to March 1, with a peak percentage of 50% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Polson 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 Polson for general outdoor tourist activities is from early 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 Polson for hot-weather activities is from mid July to early August, with a peak score in the last week of 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 Polson typically lasts for 4.9 months (150 days), from around May 4 to around October 2, rarely starting before April 16 or after May 21, and rarely ending before September 15 or after October 17.
Time Spent in Various Temperature Bands and the Growing Season
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 Polson should appear around May 3, only rarely appearing before April 22 or after May 18.
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 3.2 months, from May 14 to August 19, with an average daily incident shortwave energy per square meter above 6.2 kWh. The brightest day of the year is July 14, with an average of 7.5 kWh.
The darker period of the year lasts for 3.6 months, from October 26 to February 15, with an average daily incident shortwave energy per square meter below 2.4 kWh. The darkest day of the year is December 23, with an average of 1.1 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Polson are 47.694 deg latitude, -114.163 deg longitude, and 2,979 ft elevation.
The topography within 2 miles of Polson contains significant variations in elevation, with a maximum elevation change of 528 feet and an average elevation above sea level of 2,999 feet. Within 10 miles contains significant variations in elevation (5,049 feet). Within 50 miles also contains extreme variations in elevation (7,320 feet).
The area within 2 miles of Polson is covered by sparse vegetation (33%), water (31%), and grassland (15%), within 10 miles by sparse vegetation (32%) and water (18%), and within 50 miles by trees (42%) and sparse vegetation (26%).
This report illustrates the typical weather in Polson, 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 Polson.
For each station, the records are corrected for the elevation difference between that station and Polson 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 Polson is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Polson and a given station.
The stations contributing to this reconstruction are: Glacier Park International Airport (50%, 68 kilometers, north); Missoula International Airport (35%, 86 kilometers, south); and Mullan Pass, Mullan Pass Vor (16%, 114 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 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.