PROSSER, Wash. – After a cold spring spent wondering whether summer would ever come, central Washington spent October wondering whether the autumn chill would ever arrive.
“The relatively warm autumn helped many crops catch up from the cold spring and cool summer,” said Washington State University AgWeatherNet director Gerrit Hoogenboom. The mild overnight low temperatures experienced during most of October were a benefit to the fruit industry.
 
The first autumn frost arrived later than normal and extended the growing season well into October, allowing growers more time to harvest apples, grapes and other fall crops that were delayed by a cool spring.
 
A pattern that featured a parade of weak and mild weather systems passing through Washington kept temperatures warmer than normal during October. A mild southwesterly flow along with periodic night-time cloudiness and high dew point temperatures caused particularly elevated overnight temperatures.
 
The accumulated Growing Degree Day (GDD) values have increased significantly since late summer across much of the state. Many areas that observed record low GDD values as of mid-summer have now caught up with the 2010 values that were only slightly below normal.
 
“Low temperatures in central Washington were well above normal during October,” said Loyd. “In fact, overnight low temperatures at the Moxee station were five degrees above normal – the warmest since we’ve been keeping records.” According to Ag Weather Net meteorologist Nic Loyd, the frost-prone AgWeatherNet station at Moxee did not record its first sub-freezing temperature until Oct. 24, nearly a month later than the average first frost date of September 28. Prior to this year, the latest first frost at Moxee occurred on Oct. 6.
 
After six consecutive months of below average temperatures in central, the last three months have been warmer than normal. Certain locations recorded daily maximum and minimum temperature values that were more than 15 degrees above normal during the final two weekends of October. The minimum temperature on October 22 at the Columbia Basin College weather station in Pasco was a mild 56 degrees, while the high temperature on October 30 at the College Place weather station near Walla Walla was a balmy 72 degrees.
 
Visit WSU AgWeatherNet and set up weather alerts and much more at http://weather.wsu.edu.