Average Weather in September in Sunnyside Washington, United States
In Sunnyside, the month of September is characterized by rapidly falling daily high temperatures, with daily highs decreasing by 12°F, from 86°F to 74°F over the course of the month, and rarely exceeding 96°F or dropping below 65°F.
Daily low temperatures decrease by 9°F, from 56°F to 46°F, rarely falling below 38°F or exceeding 63°F.
For reference, on July 30, the hottest day of the year, temperatures in Sunnyside typically range from 62°F to 94°F, while on December 23, the coldest day of the year, they range from 26°F to 37°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 Sunnyside experiences increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 26% to 37%.
The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 74% of the time.
For reference, on January 16, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 65%, while on August 4, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 83%.
Cloud Cover in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Sunnyside, the chance of a wet day over the course of September is gradually increasing, starting the month at 4% and ending it at 7%.
For reference, the year's highest daily chance of a wet day is 23% on December 1, and its lowest chance is 2% on August 16.
Probability of Precipitation in September
The average sliding 31-day rainfall during September in Sunnyside is essentially constant, remaining about 0.3 inches throughout, and rarely exceeding 0.8 inches or falling below -0.0 inches.
Average Monthly Rainfall in September
Over the course of September in Sunnyside, 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, 34 minutes, implying an average daily decrease of 3 minutes, 14 seconds, and weekly decrease of 22 minutes, 39 seconds.
The shortest day of the month is September 30, with 11 hours, 43 minutes of daylight and the longest day is September 1, with 13 hours, 17 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Sunnyside is 6:20 AM on September 1 and the latest sunrise is 37 minutes later at 6:57 AM on September 30.
The latest sunset is 7:38 PM on September 1 and the earliest sunset is 57 minutes earlier at 6:41 PM on September 30.
Daylight saving time is observed in Sunnyside during 2017, 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 5:07 AM and sets 15 hours, 48 minutes later, at 8:55 PM, while on December 21, the shortest day of the year, it rises at 7:40 AM and sets 8 hours, 36 minutes later, at 4:16 PM.
Sunrise & Sunset with Twilight in September
The chance that a given day will be muggy in Sunnyside is essentially constant during September, remaining around 0% throughout.
For reference, on July 15, 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 Sunnyside is essentially constant during September, remaining around 3.9 miles per hour throughout.
For reference, on March 31, the windiest day of the year, the daily average wind speed is 4.7 miles per hour, while on September 9, the calmest day of the year, the daily average wind speed is 3.9 miles per hour.
The lowest daily average wind speed during September is 3.9 miles per hour on September 9.
Average Wind Speed in September
Wind Direction in September
The average daily incident shortwave solar energy in Sunnyside is rapidly decreasing during September, falling by 1.7 kWh, from 5.9 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 Sunnyside are 46.324 deg latitude, -120.009 deg longitude, and 778 ft elevation.
The topography within 2 miles of Sunnyside contains only modest variations in elevation, with a maximum elevation change of 308 feet and an average elevation above sea level of 768 feet. Within 10 miles contains only modest variations in elevation (2,116 feet). Within 50 miles contains large variations in elevation (5,597 feet).
The area within 2 miles of Sunnyside is covered by cropland (55%) and artificial surfaces (45%), within 10 miles by cropland (61%) and shrubs (25%), and within 50 miles by shrubs (60%) and cropland (27%).
This report illustrates the typical weather in Sunnyside 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 Sunnyside.
For each station, the records are corrected for the elevation difference between that station and Sunnyside 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 Sunnyside is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Sunnyside and a given station.
The stations contributing to this reconstruction are: Hanford (43%, 41 kilometers, northeast); Yakima Air Terminal Airport (32%, 49 kilometers, northwest); Hermiston Municipal Airport (16%, 80 kilometers, southeast); and The Dalles Municipal Airport (9%, 119 kilometers, southwest).
Time zones for aiports and weather stations are provided by AskGeo.com .