Average Weather in September in Four Corners Montana, United States
Daily high temperatures decrease by 13°F, from 78°F to 65°F, rarely falling below 49°F or exceeding 88°F.
Daily low temperatures decrease by 8°F, from 45°F to 37°F, rarely falling below 28°F or exceeding 53°F.
For reference, on July 27, the hottest day of the year, temperatures in Four Corners typically range from 50°F to 84°F, while on December 30, the coldest day of the year, they range from 13°F to 30°F.
Average High and Low Temperature in September
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
The month of September in Four Corners experiences increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 31% to 39%.
The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 69% of the time.
For reference, on March 19, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 64%, while on July 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 77%.
Cloud Cover Categories in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Four Corners, the chance of a wet day over the course of September is essentially constant, remaining around 18% throughout.
For reference, the year's highest daily chance of a wet day is 40% on June 2, and its lowest chance is 11% on January 27.
Over the course of September in Four Corners, the chance of a day with only rain decreases from 19% to 17%, the chance of a day with mixed snow and rain remains an essentially constant 1% throughout, and the chance of a day with only snow remains an essentially constant 0% throughout.
Probability of Precipitation in September
The average sliding 31-day rainfall during September in Four Corners is essentially constant, remaining about 1.1 inches throughout, and rarely exceeding 2.1 inches or falling below 0.2 inches.
The highest average 31-day accumulation is 1.1 inches on September 19.
Average Monthly Rainfall in September
Over the course of September in Four Corners, 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, 32 minutes, implying an average daily decrease of 3 minutes, 9 seconds, and weekly decrease of 22 minutes, 6 seconds.
The shortest day of the month is September 30, with 11 hours, 45 minutes of daylight and the longest day is September 1, with 13 hours, 16 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Four Corners is 6:46 AM on September 1 and the latest sunrise is 36 minutes later at 7:21 AM on September 30.
The latest sunset is 8:02 PM on September 1 and the earliest sunset is 56 minutes earlier at 7:06 PM on September 30.
Daylight saving time is observed in Four Corners during 2018, 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 5:35 AM and sets 15 hours, 42 minutes later, at 9:17 PM, while on December 21, the shortest day of the year, it rises at 8:02 AM and sets 8 hours, 41 minutes later, at 4:43 PM.
Sunrise & Sunset with Twilight in September
The chance that a given day will be muggy in Four Corners is essentially constant during September, remaining around 0% throughout.
For reference, on June 30, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in September
The average hourly wind speed in Four Corners is gradually increasing during September, increasing from 5.4 miles per hour to 6.0 miles per hour over the course of the month.
For reference, on January 10, the windiest day of the year, the daily average wind speed is 8.6 miles per hour, while on August 5, the calmest day of the year, the daily average wind speed is 4.9 miles per hour.
Average Wind Speed in September
Wind Direction in September
The growing season in Four Corners typically lasts for 3.6 months (111 days), from around May 27 to around September 15, rarely starting before May 8 or after June 16, and rarely ending before August 28 or after October 3.
During September in Four Corners, the chance that a given day is within the growing season is very rapidly decreasing falling from 84% to 14% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in September
The average accumulated growing degree days in Four Corners are increasing during September, increasing by 230°F, from 1,436°F to 1,667°F, over the course of the month.
Growing Degree Days in September
The average daily incident shortwave solar energy in Four Corners is rapidly decreasing during September, falling by 1.6 kWh, from 6.0 kWh to 4.3 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in September
For the purposes of this report, the geographical coordinates of Four Corners are 45.630 deg latitude, -111.186 deg longitude, and 4,918 ft elevation.
The topography within 2 miles of Four Corners contains only modest variations in elevation, with a maximum elevation change of 466 feet and an average elevation above sea level of 4,896 feet. Within 10 miles contains only modest variations in elevation (4,170 feet). Within 50 miles also contains extreme variations in elevation (7,398 feet).
The area within 2 miles of Four Corners is covered by cropland (72%) and grassland (22%), within 10 miles by cropland (42%) and grassland (32%), and within 50 miles by grassland (34%) and trees (31%).
This report illustrates the typical weather in Four Corners year round, 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 Four Corners.
For each station, the records are corrected for the elevation difference between that station and Four Corners 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 Four Corners is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Four Corners and a given station.
The stations contributing to this reconstruction are: Gallatin Field Airport (72%, 18 kilometers, north); Mission Field (18%, 58 kilometers, east); Dillon Airport (7%, 115 kilometers, west); and West Yellowstone (3.9%, 135 kilometers, southeast).
Time zones for aiports and weather stations are provided by AskGeo.com .