AgWeatherNet September 2014 Weather Review for Washington

Warm Weather Continues

Nic Loyd, Meteorologist, 509-786-9357
Gerrit Hoogenboom, Director, 509-786-9371

Overview
September marks the seventh consecutive month of abnormal warmth in Washington. Although last month's heat was hardly record breaking, conditions were nonetheless appreciably warmer than normal for both the day-time and night-time periods. Locations west of the Cascades such as Mt. Vernon were especially balmy, with temperatures of more than 2 degree above normal. Thus, 2014 continues the recent trend, though to a lesser degree, of unusually hot Septembers.

An impressive 1.58 inches of rain fell at Mt. Vernon on September 2nd, while Vancouver soared to 95 degrees just four days later. Much of the first two-thirds of the month was fairly dry with large diurnal ranges. One of the more notable weather episodes of September was the shot of dry air that arrived during the second week of the month, and produced some chilly low temperatures on the mornings of the 11th to the 13th. On September 11th, the low at Pullman was 26 degrees, which was their coldest reading since April 13th. Increasingly unsettled conditions arrived later in September, and a slow moving front spawned 2.34 inches of rain at Tokeland on the 23rd. After a brief dry spell, rain returned to western areas on the 29th and 30th, as a fast-moving clipper-type disturbance passed through the state. Overall, September was a typically variable and relatively unremarkable weather month.

September 2014 Average Temperatures (°F)
Location (Period of Record) Maximum Anomaly Minimum Anomaly Mean Anomaly Soil Temperature
8 inches
Prosser (WSU IAREC; 1989-2014)
79.2
0.9
49.9
1.9
64.4
1.8
67.7
Moxee (1989-2014)
79.3
0.1
44.2
2.1
61.0
1.1
63.0
Mt Vernon (WSU NWREC; 1994-2014)
70.7
2.4
51.1
2.1
60.4
2.2
62.4
Wenatchee (WSU TFREC; 1994-2014)
79.2
0.4
50.2
1.0
64.0
0.7
66.7
Tri-Cities (1995-2014)
82.5
1.5
54.0
2.3
68.1
2.1
75.4
Walla Walla (1993-2014)
79.9
2.3
52.3
0.9
65.1
1.0
73.3
Moses Lake (1989-2014)
79.3
0.9
48.2
1.2
63.4
0.8
71.8
Omak (Pogue Flat; 2005-2014)
77.2
NA
49.2
NA
62.9
NA
68.6
Royal City East (2008-2014)
77.4
NA
52.0
NA
64.0
NA
69.9
Pullman (2008-2014)
75.6
NA
42.5
NA
59.9
NA
65.0
Long Beach (WSU Long Beach; 2005-2014)
71.5
NA
51.1
NA
60.1
NA
64.5
Sequim (2008-2014)
70.6
NA
47.8
NA
59.0
NA
62.1
Seattle (2011-2014)
74.3
NA
54.7
NA
63.2
NA
67.1
Vancouver (WSU RE; 2008-2014)
77.9
NA
51.4
NA
64.6
NA
64.5
2014 Rainfall and Evapotranspiration (ET) (inches)
Location (Period of Record) Rainfall ET Net
September 2014 September (Rain - ET)
Prosser (WSU IAREC; 1989-2014)
0.10
4.20
5.91
-5.81
Moxee (1989-2014)
0.32
3.71
4.86
-4.54
Mt. Vernon (WSU NWREC; 1994-2014)
2.64
25.93
2.90
-0.26
Wenatchee (WSU TFREC; 1994-2014)
0.23
5.32
4.39
-4.16
Tri-Cities (1995-2014)
0.00
3.44
6.66
-6.66
Walla Walla (1993-2014)
0.25
9.59
5.22
-4.97
Moses Lake (1989-2014)
0.06
3.26
6.42
-6.36
Omak (Pogue Flat; 2005-2014)
0.35
5.10
4.42
-4.07
Royal City East (2008-2014)
0.24
3.84
5.62
-5.38
Pullman (2008-2014)
0.16
10.28
6.94
-6.78
Long Beach (WSU Long Beach; 2005-2014)
2.99
41.95
2.94
0.05
Sequim (2008-2014)
0.71
10.49
3.37
-2.66
Seattle (2011-2014)
2.67
29.32
3.33
-0.66
Vancouver (WSU RE; 2008-2014)
1.09
23.70
4.77
-3.68
September 2014 Daily Rainfall Time Series Graph for Prosser September 2014 Daily Rainfall Time Series Graph for Long Beach

September Weather
Early September-Hot Western Weather
September's weather began seasonally, as highs on the 2nd reached the mid 70s to mid 80s east of the Cascades, and 60s to mid 70s in the west. Significant rain fell in northwestern Washington, including 1.58 inches at Mt. Vernon. Winds were breezy and southwesterly in eastern areas.

Highs on the 5th reached the 70s and 80s, including 88 degrees at Long Beach and Vancouver, while lows were in the mid 30s to low 60s, including 34 degrees at Pullman. Highs on the 6th climbed into the upper 70s to mid 90s in the west, including 95 degrees at Vancouver, and mainly the 80s to around 90 degrees in the east. Lows ranged from 35 degrees at Pullman to 67 degrees at Wahluke Slope. High temperatures on September 7th peaked in the mid 80s to low 90s east of the Cascades, and 80s in interior western areas, but only the 60s at the coast. Lows were in the upper 30s to mid 60s.

Mid September-Cool Nights then Warmer
Highs on the 11th were mainly in the mid 60s to mid 70s in the east, and upper 60s to around 80 degrees west of the Cascades. Lows were mainly in the 30s to around 60 degrees, although Pullman plummeted to 26 degrees. A back door cold front from the north brought very dry air to the eastern part of the state.

Highs on the 17th varied from 65 degrees at Sequim to 91 degrees at LaCrosse, with lows ranging from 46 degrees at Pullman to 66 degrees at Huntsville, as clouds streamed in from the south. Light rain fell in western areas, with 0.23 inches at Sequim. Highs on the 18th reached the mid 60s to low 70s in the west, and mainly 70s to mid 80s east of the Cascades. Lows were in the upper 40s to 60s. Rain fell in northwestern Washington, with 0.25 inches at Ten Mile (Whatcom County), and breezy southwesterly winds in eastern areas.

Highs on the 20th reached the 70s to 80s in most of western Washington, except 93 degrees at Vancouver. Lows fell into the 40s to mid 60s. Winds turned offshore, and skies were mainly sunny. Highs on the 21st climbed into the mid 80s to low 90s in the east, and upper 60s to 80s in the west. Lows were in the 40s to near 70 degrees.

Late September-From Hot and Dry to Unsettled
Highs on the 23rd climbed into the 60s in the west, and mid 60s to low 80s in the east. Lows fell into the 50s to mid 60s. Rain fell in the west, with 2.34 inches at Tokeland, as a slow moving front pushed into Washington. Winds were generally southeasterly.

Rain-cooled highs on the 24th reached only into the 60s in central Washington, including 61 degrees at Gleed, and 70s in eastern areas. Rain fell in western and central Washington, with 0.86 inches at Poulsbo South, and 0.31 inches at Parker. Aside from southeastern Washington, the sunniest place in the state was the coast. Winds were southerly and breezy, and gusted to 39 mph at Hundred Circles.

Highs on the 26th climbed into the 60s and 70s, with lows in the 40s and 50s. More than 0.9 inches of rain fell in parts of western Washington. Highs on the 29th reached the low to mid 60s in the west, but the 70s to low 80s in central Washington. Lows were in the 40s to mid 60s. A quick moving disturbance brought some rain to parts of the west, including 0.44 inches at 21 Acres, and also 0.25 inches at Huntsville. Highs on the 30th reached the 60s to mid 70s, but only 57 degrees at Anatone, with lows in the upper 30s to mid 50s, and 0.27 inches of rainfall at Garfield East.

September 2014 Daily Temperatures
2014 temperature Time Series Graph for Prosser 2014 temperature Time Series Graph for Moxee
2014 temperature Time Series Graph for Wenatchee 2014 temperature Time Series Graph for Tri-Cities
2014 temperature Time Series Graph for:Walla Walla September 2014 Temperature Time Series Graph for WSU
September 2014 Temperature Time Series Graph for WSUMoses Lake September 2014 Temperature Time Series Graph for WSU Omak
September 2014 Temperature Time Series Graph for WSU Long Beach September 2014 Temperature Time Series Graph for WSU Mt. Vernon

September-By The Numbers
The average September temperature at Prosser (WSU IAREC) was 64.4°F, which is 1.8 degrees above average. The average high temperature was 79.2°F, which is 0.9 degrees above average. The average low temperature was 49.9°F, which is 1.9 degrees above average. The maximum temperature recorded last month was 89.6°F on September 7th, while the coolest daily high was 66.5°F on September 24th. Low temperatures ranged from 59.0°F on September 23rd to 38.4°F on September 12th. Daily average temperatures ranged from 70.0°F on the 22nd to 57.6°F on the 12th. The monthly precipitation total was 0.10 inches. The average wind speed was 4.0 mph, and the average 8 inch soil temperature was 67.7°F. Wenatchee (WSU TFREC) recorded an average temperature of 64.0°F, which is 0.7 degrees above average, while Walla Walla's average monthly temperature of 65.1°F was 1.0 degrees above average. Pullman was one of the cooler spots in eastern Washington, with an average September temperature of 59.9°F. In western Washington, Mt. Vernon's average temperature was 60.4°F, which is 2.2 degrees above average.


Notable September Events
  • September 2nd: 1.58 inches of rain fell at Mt. Vernon.
  • September 6th: The high temperature at Vancouver soared to 95 degrees.
  • September 11th: The low temperature at Pullman plummeted to 26 degrees.
  • September 23rd: 2.34 inches of rain fell at Tokeland.

September Temperature Extremes (°F)
  Observed in 2014 Record Monthly Extremes
Site (Period of Record) Warmest Date Coldest Date Warmest Date Coldest Date
Prosser (WSU IAREC; 1989-2014)
89.6
9/7/2014
38.4
9/12/2014
97.0
9/2/1998
30.7
9/23/2000
Moxee (1989-2014)
88.7
9/7/2014
32.4
9/12/2014
98.3
9/5/2003
23.5
9/23/2000
Mt. Vernon (WSU NWREC; 1994-2014)
81.4
9/6/2014
39.2
9/12/2014
83.0
9/3/2003
35.8
9/23/2000
Wenatchee (WSU TFREC; 1994-2014)
90.4
9/7/2014
35.5
9/12/2014
98.9
9/1/1998
29.6
9/23/2000
Tri-Cities (1995-2014)
90.3
9/7/2014
42.5
9/12/2014
98.3
9/1/1998
32.8
9/23/1996
Walla Walla (1992-2014)
89.7
9/7/2014
39.5
9/12/2014
97.6
9/15/2013
30.6
9/23/2000
Moses Lake (1989-2014)
89.5
9/7/2014
34.5
9/12/2014
98.3
9/3/2006
27.6
9/28/1999
Omak (Pogue Flat; 2005-2014)
88.5
9/7/2014
32.7
9/12/2014
97.3
9/9/2011
30.6
9/29/2007
Royal City East (2008-2014)
88.5
9/21/2014
41.8
9/12/2014
93.3
9/12/2013
36.9
9/30/2009
Pullman (2008-2014)
87.5
9/21/2014
26.1
9/11/2014
94.7
9/24/2011
25.3
9/12/2012
Long Beach (WSU Long Beach; 2005-2014)
89.1
9/6/2014
42.6
9/14/2014
96.0
9/22/2009
30.2
9/17/2010
Sequim (2008-2014)
79.0
9/6/2014
35.8
9/12/2014
80.9
9/8/2011
33.0
9/29/2011
Seattle (2011-2014)
89.9
9/6/2014
45.9
9/12/2014
NA
NA
NA
NA
Vancouver (WSU RE; 2008-2014)
94.8
9/6/2014
41.1
9/12/2014
95.9
9/11/2013
35.8
9/23/2008

Agriculture Report
Conditions in mid September were generally ideal for harvest, with good crop quality in most cases. As of September 14th, hop and onion harvest continued in eastern Washington, as did tomato and pepper harvest in western areas. Pear, peach, and wine grape harvest also continued, and winter wheat planting was nearing completion.

As of September 29th, recent rainfall in western areas had somewhat replenished the depleted soil moisture, and eastern rainfall was welcomed by dryland winter wheat growers. Harvest of apples and corn continued, as pumpkins and gourds became ready for sale. (National Agricultural Statistics Service)

April 1 to September 30 Accumulated Growing Degree Days
  Base Temperature (°F)
32 43 50
Location 2014 5 Year Avg Difference 2014 5 Year Avg Difference 2014 5 Year Avg Difference
Prosser (WSU IAREC)
6178
5752
426
4165
3743
422
2888
2525
363
Tri-Cities
6786
6316
470
4773
4304
469
3492
3061
431
Walla Walla
6326
5909
417
4313
3901
412
3041
2685
356
Wenatchee (WSU TFREC)
6455
6043
412
4442
4037
405
3168
2822
346
Moxee
5621
5275
346
3608
3285
323
2372
2122
250
Omak (Pogue Flat)
6085
5745
340
4072
3743
329
2823
2557
266
Moses Lake
6157
5788
369
4144
3782
362
2873
2571
302
Pullman
4884
4574
310
2882
2621
261
1760
1549
211
Royal City East
6147
5799
348
4134
3790
344
2857
2578
279
Mt. Vernon (WSU NWREC)
5104
4677
427
3091
2670
421
1826
1473
353
Long Beach (WSU Long Beach)
4617
4240
377
2604
2233
371
1385
1072
313
Sequim
4778
4251
527
2765
2254
511
1553
1126
427

GDD are calculated by subtracting a base temperature from the average daily temperature (°F). If the resulting value is less than 0, then it is set to 0. Thus GDD are always 0 or greater.

GDD = (Tmax+Tmin)/2 - Tbase


This Month in History
On September 15th, 2013, the high temperature at College Place soared to 101 degrees.

Climate Outlook
According to the Climate Prediction Center, above normal temperatures and below normal precipitation are likely for October and well into 2015. El Niño continues to develop, and is expected to peak at weak or moderate strength during the early winter.

Washington State University