Average Weather in September in Grain Valley Missouri, United States
Daily high temperatures decrease by 11°F, from 84°F to 73°F, rarely falling below 62°F or exceeding 93°F.
Daily low temperatures decrease by 12°F, from 65°F to 54°F, rarely falling below 42°F or exceeding 74°F.
For reference, on July 21, the hottest day of the year, temperatures in Grain Valley typically range from 71°F to 89°F, while on January 22, the coldest day of the year, they range from 24°F to 40°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 Grain Valley experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 31% throughout the month.
The clearest day of the month is September 19, with clear, mostly clear, or partly cloudy conditions 70% of the time.
For reference, on February 12, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 52%, while on August 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 71%.
Cloud Cover Categories in September
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 Grain Valley, the chance of a wet day over the course of September is decreasing, starting the month at 31% and ending it at 26%.
For reference, the year's highest daily chance of a wet day is 44% on June 8, and its lowest chance is 11% on January 12.
Probability of Precipitation in September
The average sliding 31-day rainfall during September in Grain Valley is gradually decreasing, starting the month at 3.9 inches, when it rarely exceeds 7.3 inches or falls below 1.4 inches, and ending the month at 3.6 inches, when it rarely exceeds 7.5 inches or falls below 0.9 inches.
The highest average 31-day accumulation is 4.0 inches on September 14.
Average Monthly Rainfall in September
Over the course of September in Grain Valley, 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, 12 minutes, implying an average daily decrease of 2 minutes, 30 seconds, and weekly decrease of 17 minutes, 30 seconds.
The shortest day of the month is September 30, with 11 hours, 49 minutes of daylight and the longest day is September 1, with 13 hours, 2 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Grain Valley is 6:45 AM on September 1 and the latest sunrise is 26 minutes later at 7:11 AM on September 30.
The latest sunset is 7:47 PM on September 1 and the earliest sunset is 46 minutes earlier at 7:00 PM on September 30.
Daylight saving time is observed in Grain Valley 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 5:51 AM and sets 14 hours, 55 minutes later, at 8:45 PM, while on December 21, the shortest day of the year, it rises at 7:32 AM and sets 9 hours, 26 minutes later, at 4:57 PM.
Sunrise & Sunset with Twilight in September
The chance that a given day will be muggy in Grain Valley is very rapidly decreasing during September, falling from 44% to 10% over the course of the month.
For reference, on July 23, the muggiest day of the year, there are muggy conditions 68% of the time, while on December 2, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in September
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Grain Valley is increasing during September, increasing from 8.5 miles per hour to 9.7 miles per hour over the course of the month.
For reference, on April 1, the windiest day of the year, the daily average wind speed is 12.4 miles per hour, while on August 7, the calmest day of the year, the daily average wind speed is 7.8 miles per hour.
Average Wind Speed in September
Wind Direction in September
The growing season in Grain Valley typically lasts for 6.8 months (209 days), from around April 4 to around October 30, rarely starting before March 14 or after April 22, and rarely ending before October 12 or after November 18.
The month of September in Grain Valley is reliably fully within the growing season.
Time Spent in Various Temperature Bands and the Growing Season in September
The average accumulated growing degree days in Grain Valley are rapidly increasing during September, increasing by 540°F, from 3,258°F to 3,798°F, over the course of the month.
Growing Degree Days in September
The average daily incident shortwave solar energy in Grain Valley is decreasing during September, falling by 1.1 kWh, from 5.8 kWh to 4.7 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 Grain Valley are 39.015 deg latitude, -94.199 deg longitude, and 830 ft elevation.
The topography within 2 miles of Grain Valley contains only modest variations in elevation, with a maximum elevation change of 213 feet and an average elevation above sea level of 816 feet. Within 10 miles also contains only modest variations in elevation (387 feet). Within 50 miles contains only modest variations in elevation (535 feet).
The area within 2 miles of Grain Valley is covered by artificial surfaces (51%), cropland (31%), and trees (18%), within 10 miles by cropland (58%) and trees (24%), and within 50 miles by cropland (77%) and trees (12%).
This report illustrates the typical weather in Grain Valley 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Grain Valley.
For each station, the records are corrected for the elevation difference between that station and Grain Valley 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 Grain Valley is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Grain Valley and a given station.
The stations contributing to this reconstruction are: Lee's Summit Municipal Airport (64%, 16 kilometers, west); Midwest National Air Center (20%, 37 kilometers, north); and Skyhaven Airport (16%, 43 kilometers, southeast).
Time zones for aiports and weather stations are provided by AskGeo.com .