September Weather in Plentywood Montana, United States
Daily high temperatures decrease by 14°F, from 77°F to 63°F, rarely falling below 48°F or exceeding 89°F.
Daily low temperatures decrease by 11°F, from 50°F to 39°F, rarely falling below 29°F or exceeding 59°F.
For reference, on July 30, the hottest day of the year, temperatures in Plentywood typically range from 56°F to 83°F, while on January 5, the coldest day of the year, they range from 4°F to 20°F.
Average High and Low Temperature in September in Plentywood
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. The horizontal axis is the day, 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 September in Plentywood
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
The month of September in Plentywood experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 35% to 42%.
The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 65% of the time.
For reference, on February 20, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 62%, while on July 29, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 74%.
Cloud Cover Categories in September in Plentywood
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. In Plentywood, the chance of a wet day over the course of September is decreasing, starting the month at 17% and ending it at 12%.
For reference, the year's highest daily chance of a wet day is 33% on June 11, and its lowest chance is 3% on February 12.
Probability of Precipitation in September in Plentywood
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during September in Plentywood is essentially constant, remaining about 0.9 inches throughout, and rarely exceeding 2.2 inches or falling below 0.1 inches.
Average Monthly Rainfall in September in Plentywood
Over the course of September in Plentywood, the length of the day is rapidly decreasing. From the start to the end of the month, the length of the day decreases by 1 hour, 42 minutes, implying an average daily decrease of 3 minutes, 32 seconds, and weekly decrease of 24 minutes, 42 seconds.
The shortest day of the month is September 30, with 11 hours, 42 minutes of daylight and the longest day is September 1, with 13 hours, 24 minutes of daylight.
Hours of Daylight and Twilight in September in Plentywood
The earliest sunrise of the month in Plentywood is 6:15 AM on September 1 and the latest sunrise is 41 minutes later at 6:56 AM on September 30.
The latest sunset is 7:39 PM on September 1 and the earliest sunset is 1 hour, 1 minute earlier at 6:38 PM on September 30.
Daylight saving time is observed in Plentywood during 2021, but it neither starts nor ends during September, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 4:55 AM and sets 16 hours, 10 minutes later, at 9:05 PM, while on December 21, the shortest day of the year, it rises at 7:48 AM and sets 8 hours, 16 minutes later, at 4:04 PM.
Sunrise & Sunset with Twilight in September in Plentywood
The figure below presents a compact representation of key lunar data for September 2021. 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.
Moon Rise, Set & Phases in September in Plentywood
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 chance that a given day will be muggy in Plentywood is essentially constant during September, remaining around 0% throughout.
For reference, on July 17, the muggiest day of the year, there are muggy conditions 4% of the time, while on September 22, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in September in Plentywood
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 Plentywood is gradually increasing during September, increasing from 10.3 miles per hour to 11.0 miles per hour over the course of the month.
For reference, on March 31, the windiest day of the year, the daily average wind speed is 12.0 miles per hour, while on July 31, the calmest day of the year, the daily average wind speed is 9.5 miles per hour.
Average Wind Speed in September in Plentywood
The hourly average wind direction in Plentywood throughout September is predominantly from the west, with a peak proportion of 35% on September 30.
Wind Direction in September in Plentywood
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 Plentywood typically lasts for 4.3 months (132 days), from around May 14 to around September 23, rarely starting before April 25 or after June 2, and rarely ending before September 6 or after October 12.
During September in Plentywood, the chance that a given day is within the growing season is very rapidly decreasing falling from 97% to 30% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in September in Plentywood
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.
The average accumulated growing degree days in Plentywood are increasing during September, increasing by 240°F, from 1,768°F to 2,009°F, over the course of the month.
Growing Degree Days in September in Plentywood
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 in Plentywood is rapidly decreasing during September, falling by 1.6 kWh, from 5.4 kWh to 3.8 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in September in Plentywood
For the purposes of this report, the geographical coordinates of Plentywood are 48.775 deg latitude, -104.562 deg longitude, and 2,044 ft elevation.
The topography within 2 miles of Plentywood contains only modest variations in elevation, with a maximum elevation change of 256 feet and an average elevation above sea level of 2,083 feet. Within 10 miles contains only modest variations in elevation (669 feet). Within 50 miles contains significant variations in elevation (1,129 feet).
The area within 2 miles of Plentywood is covered by grassland (86%) and cropland (14%), within 10 miles by grassland (62%) and cropland (38%), and within 50 miles by cropland (55%) and grassland (44%).
This report illustrates the typical weather in Plentywood, 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 5 weather stations near enough to contribute to our estimation of the temperature and dew point in Plentywood.
For each station, the records are corrected for the elevation difference between that station and Plentywood 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 Plentywood is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Plentywood and a given station.
The stations contributing to this reconstruction are: Coronach Spc (CWAQ, 28%, 74 kilometers, northwest); Crosby Municipal Airport (KD50, 20%, 94 kilometers, east); Sloulin Field International Airport (KISN, 20%, 96 kilometers, southeast); Lyman Clayton Airport (KOLF, 17%, 106 kilometers, southwest); and Weyburn Automatic Weather Reporting System (CWWF, 15%, 117 kilometers, northeast).
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.