Average Weather in September in Altamont Tennessee, United States
Daily high temperatures decrease by 9°F, from 82°F to 73°F, rarely falling below 63°F or exceeding 88°F.
Daily low temperatures decrease by 10°F, from 62°F to 51°F, rarely falling below 39°F or exceeding 67°F.
For reference, on July 21, the hottest day of the year, temperatures in Altamont typically range from 65°F to 85°F, while on January 29, the coldest day of the year, they range from 28°F to 45°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 Altamont experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 35% throughout the month. The lowest chance of overcast or mostly cloudy conditions is 33% on September 21.
The clearest day of the month is September 21, with clear, mostly clear, or partly cloudy conditions 67% of the time.
For reference, on January 3, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 58%, while on September 20, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 67%.
Cloud Cover Categories in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Altamont, the chance of a wet day over the course of September is decreasing, starting the month at 29% and ending it at 25%.
For reference, the year's highest daily chance of a wet day is 44% on July 9, and its lowest chance is 21% on October 15.
Probability of Precipitation in September
The average sliding 31-day rainfall during September in Altamont is gradually increasing, starting the month at 2.9 inches, when it rarely exceeds 5.4 inches or falls below 1.1 inches, and ending the month at 3.3 inches, when it rarely exceeds 6.2 inches or falls below 1.1 inches.
The highest average 31-day accumulation is 3.4 inches on September 23.
Average Monthly Rainfall in September
Over the course of September in Altamont, 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, 4 minutes, implying an average daily decrease of 2 minutes, 12 seconds, and weekly decrease of 15 minutes, 21 seconds.
The shortest day of the month is September 30, with 11 hours, 51 minutes of daylight and the longest day is September 1, with 12 hours, 55 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Altamont is 6:15 AM on September 1 and the latest sunrise is 22 minutes later at 6:37 AM on September 30.
The latest sunset is 7:09 PM on September 1 and the earliest sunset is 42 minutes earlier at 6:28 PM on September 30.
Daylight saving time is observed in Altamont 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 5:28 AM and sets 14 hours, 33 minutes later, at 8:01 PM, while on December 21, the shortest day of the year, it rises at 6:48 AM and sets 9 hours, 46 minutes later, at 4:33 PM.
Sunrise & Sunset with Twilight in September
The chance that a given day will be muggy in Altamont is very rapidly decreasing during September, falling from 50% to 12% over the course of the month.
For reference, on July 24, the muggiest day of the year, there are muggy conditions 78% of the time, while on January 14, 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 Altamont is gradually increasing during September, increasing from 3.8 miles per hour to 4.5 miles per hour over the course of the month.
For reference, on February 25, the windiest day of the year, the daily average wind speed is 6.5 miles per hour, while on July 31, the calmest day of the year, the daily average wind speed is 3.6 miles per hour.
Average Wind Speed in September
Wind Direction in September
The growing season in Altamont typically lasts for 6.3 months (192 days), from around April 11 to around October 20, rarely starting before March 25 or after April 28, and rarely ending before October 3 or after November 6.
The month of September in Altamont is very likely fully within the growing season, with the chance that a given day is in the growing season gradually decreasing from 100% to 94% 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 Altamont are rapidly increasing during September, increasing by 482°F, from 2,902°F to 3,384°F, over the course of the month.
Growing Degree Days in September
The average daily incident shortwave solar energy in Altamont is gradually decreasing during September, falling by 0.9 kWh, from 5.8 kWh to 4.9 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 Altamont are 35.430 deg latitude, -85.723 deg longitude, and 1,857 ft elevation.
The topography within 2 miles of Altamont contains significant variations in elevation, with a maximum elevation change of 499 feet and an average elevation above sea level of 1,839 feet. Within 10 miles contains significant variations in elevation (1,483 feet). Within 50 miles contains very significant variations in elevation (2,569 feet).
The area within 2 miles of Altamont is covered by trees (97%), within 10 miles by trees (89%) and cropland (11%), and within 50 miles by trees (61%) and cropland (34%).
This report illustrates the typical weather in Altamont 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 5 weather stations near enough to contribute to our estimation of the temperature and dew point in Altamont.
For each station, the records are corrected for the elevation difference between that station and Altamont 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 Altamont is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Altamont and a given station.
The stations contributing to this reconstruction are: Winchester Municipal Airport (29%, 42 kilometers, southwest); Tullahoma Regional Airport/William Northern Field (26%, 48 kilometers, west); Lovell Field (16%, 65 kilometers, southeast); Upper Cumberland Regional Airport (15%, 72 kilometers, north); and Crossville Memorial Airport (14%, 82 kilometers, northeast).
Time zones for aiports and weather stations are provided by AskGeo.com .