Average Weather in September in Spiro Oklahoma, United States
Daily high temperatures decrease by 10°F, from 91°F to 80°F, rarely falling below 70°F or exceeding 99°F.
Daily low temperatures decrease by 11°F, from 69°F to 58°F, rarely falling below 46°F or exceeding 74°F.
For reference, on July 25, the hottest day of the year, temperatures in Spiro typically range from 72°F to 94°F, while on January 7, the coldest day of the year, they range from 31°F to 50°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 Spiro experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 30% throughout the month.
The clearest day of the month is September 30, with clear, mostly clear, or partly cloudy conditions 71% of the time.
For reference, on February 17, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 48%, while on October 5, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 72%.
Cloud Cover Categories in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Spiro, the chance of a wet day over the course of September is essentially constant, remaining around 28% throughout.
For reference, the year's highest daily chance of a wet day is 44% on May 21, and its lowest chance is 18% on January 12.
Probability of Precipitation in September
The average sliding 31-day rainfall during September in Spiro is increasing, starting the month at 3.2 inches, when it rarely exceeds 5.8 inches or falls below 1.0 inches, and ending the month at 3.9 inches, when it rarely exceeds 6.9 inches or falls below 1.1 inches.
Average Monthly Rainfall in September
Over the course of September in Spiro, 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, 3 minutes, implying an average daily decrease of 2 minutes, 11 seconds, and weekly decrease of 15 minutes, 16 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, 54 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Spiro is 6:50 AM on September 1 and the latest sunrise is 22 minutes later at 7:12 AM on September 30.
The latest sunset is 7:45 PM on September 1 and the earliest sunset is 42 minutes earlier at 7:03 PM on September 30.
Daylight saving time is observed in Spiro 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 6:04 AM and sets 14 hours, 32 minutes later, at 8:36 PM, while on December 21, the shortest day of the year, it rises at 7:23 AM and sets 9 hours, 47 minutes later, at 5:10 PM.
Sunrise & Sunset with Twilight in September
The chance that a given day will be muggy in Spiro is very rapidly decreasing during September, falling from 66% to 23% over the course of the month.
For reference, on July 22, the muggiest day of the year, there are muggy conditions 87% of the time, while on January 12, 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 Spiro is gradually increasing during September, increasing from 5.0 miles per hour to 5.6 miles per hour over the course of the month.
For reference, on March 23, the windiest day of the year, the daily average wind speed is 7.5 miles per hour, while on August 3, the calmest day of the year, the daily average wind speed is 4.6 miles per hour.
Average Wind Speed in September
Wind Direction in September
The growing season in Spiro typically lasts for 7.5 months (229 days), from around March 24 to around November 8, rarely starting before March 1 or after April 16, and rarely ending before October 19 or after November 29.
The month of September in Spiro 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 Spiro are rapidly increasing during September, increasing by 662°F, from 3,949°F to 4,612°F, over the course of the month.
Growing Degree Days in September
The average daily incident shortwave solar energy in Spiro is gradually decreasing during September, falling by 0.9 kWh, from 5.9 kWh to 5.0 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 Spiro are 35.241 deg latitude, -94.620 deg longitude, and 459 ft elevation.
The topography within 2 miles of Spiro contains only modest variations in elevation, with a maximum elevation change of 200 feet and an average elevation above sea level of 479 feet. Within 10 miles contains only modest variations in elevation (558 feet). Within 50 miles contains significant variations in elevation (2,349 feet).
The area within 2 miles of Spiro is covered by cropland (81%) and artificial surfaces (10%), within 10 miles by cropland (84%) and trees (11%), and within 50 miles by trees (58%) and cropland (36%).
This report illustrates the typical weather in Spiro 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 Spiro.
For each station, the records are corrected for the elevation difference between that station and Spiro 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 Spiro is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Spiro and a given station.
The stations contributing to this reconstruction are: Robert S Kerr Airport (36%, 25 kilometers, south); Fort Smith Municipal Airport (34%, 25 kilometers, northeast); and Sallisaw Municipal Airport (30%, 27 kilometers, northwest).
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.
Time zones for aiports and weather stations are provided by AskGeo.com .