Average Weather in September in Greenville Pennsylvania, United States
Daily high temperatures decrease by 10°F, from 77°F to 67°F, rarely falling below 55°F or exceeding 85°F.
Daily low temperatures decrease by 9°F, from 58°F to 49°F, rarely falling below 39°F or exceeding 68°F.
For reference, on July 20, the hottest day of the year, temperatures in Greenville typically range from 63°F to 82°F, while on January 29, the coldest day of the year, they range from 19°F to 33°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
Topolog, Romania (5,035 miles away); Grazhdanskoye, Russia (5,559 miles); and Soleh Bon, Iran (6,337 miles) are the far-away foreign places with temperatures most similar to Greenville (view comparison).
The month of September in Greenville experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 37% throughout the month.
The clearest day of the month is September 6, with clear, mostly clear, or partly cloudy conditions 65% of the time.
For reference, on January 12, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 73%, while on August 12, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 66%.
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 Greenville, the chance of a wet day over the course of September is gradually increasing, starting the month at 30% and ending it at 32%.
For reference, the year's highest daily chance of a wet day is 39% on June 15, and its lowest chance is 18% on January 30.
Probability of Precipitation in September
The average sliding 31-day rainfall during September in Greenville is essentially constant, remaining about 3.0 inches throughout, and rarely exceeding 5.0 inches or falling below 1.5 inches.
The highest average 31-day accumulation is 3.1 inches on September 18.
Average Monthly Rainfall in September
Over the course of September in Greenville, 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, 19 minutes, implying an average daily decrease of 2 minutes, 43 seconds, and weekly decrease of 19 minutes, 3 seconds.
The shortest day of the month is September 30, with 11 hours, 47 minutes of daylight and the longest day is September 1, with 13 hours, 6 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Greenville is 6:48 AM on September 1 and the latest sunrise is 29 minutes later at 7:17 AM on September 30.
The latest sunset is 7:54 PM on September 1 and the earliest sunset is 49 minutes earlier at 7:04 PM on September 30.
Daylight saving time is observed in Greenville 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 5:48 AM and sets 15 hours, 10 minutes later, at 8:58 PM, while on December 21, the shortest day of the year, it rises at 7:44 AM and sets 9 hours, 11 minutes later, at 4:55 PM.
Sunrise & Sunset with Twilight in September
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
The chance that a given day will be muggy in Greenville is rapidly decreasing during September, falling from 21% to 4% over the course of the month.
For reference, on July 20, the muggiest day of the year, there are muggy conditions 34% 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
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Greenville is gradually increasing during September, increasing from 3.7 miles per hour to 4.3 miles per hour over the course of the month.
For reference, on January 17, the windiest day of the year, the daily average wind speed is 7.2 miles per hour, while on August 1, the calmest day of the year, the daily average wind speed is 3.5 miles per hour.
Average Wind Speed in September
The hourly average wind direction in Greenville throughout September is predominantly from the south, with a peak proportion of 35% on September 24.
Wind Direction in September
Greenville is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average surface water temperature in Greenville is decreasing during September, falling by 7°F, from 72°F to 65°F, over the course of the month.
Average Water Temperature in September
The growing season in Greenville typically lasts for 5.7 months (174 days), from around April 29 to around October 20, rarely starting before April 11 or after May 20, and rarely ending before October 2 or after November 8.
The month of September in Greenville 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 93% 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 Greenville are increasing during September, increasing by 380°F, from 2,308°F to 2,687°F, over the course of the month.
Growing Degree Days in September
The average daily incident shortwave solar energy in Greenville is decreasing during September, falling by 1.3 kWh, from 5.5 kWh to 4.2 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 Greenville are 41.404 deg latitude, -80.391 deg longitude, and 942 ft elevation.
The topography within 2 miles of Greenville contains only modest variations in elevation, with a maximum elevation change of 341 feet and an average elevation above sea level of 1,069 feet. Within 10 miles contains only modest variations in elevation (574 feet). Within 50 miles contains significant variations in elevation (1,339 feet).
The area within 2 miles of Greenville is covered by trees (62%), artificial surfaces (23%), and cropland (14%), within 10 miles by trees (54%) and cropland (41%), and within 50 miles by trees (56%) and cropland (29%).
This report illustrates the typical weather in Greenville, 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 Greenville.
For each station, the records are corrected for the elevation difference between that station and Greenville 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 Greenville is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Greenville and a given station.
The stations contributing to this reconstruction are: Port Meadville Airport (26%, 29 kilometers, northeast); Youngstown–Warren Regional Airport (29%, 29 kilometers, southwest); New Castle Municipal Airport (17%, 41 kilometers, south); Venango Regional Airport (14%, 44 kilometers, east); and Ashtabula County Airport (14%, 49 kilometers, northwest).
Time zones for airports and weather stations are provided by AskGeo.com .