AgWeatherNet Summer 2012 Weather Review for Washington

A Summer of Weather Extremes Concludes with Hot Temperatures in August

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

Overview
The Good, the Bad, and the Ugly of northwest weather were all on display during Washington's summer of 2012. Despite a good ending that featured sunny and pleasant late August weather, much of the summer weather ranged from bad to downright ugly. From strong thunderstorms with heavy rain and large hail, to heat waves and raging wildfires causing smoke filled skies, a diverse spectrum of weather concerns confronted Washington over the course of the season. Similar to 2011, the summer of 2012 began cool and wet, and ended hot and dry. The significant rainfall in June left many people feeling as if we experienced too much of a good thing, while a mostly rain-free August left the parched and fire-ravaged Northwest begging for a welcome rain shower. Despite some similarities, the two summers were also different by several measures. The most striking distinction is the severe weather that affected Washington this year during the middle of July, which was absent last summer. The stormy period culminated with a thunderstorm outbreak on July 20th that led to locally devastating and yet highly variable levels of hail-induced crop damage in farms and orchards across central and eastern Washington. Some AgWeatherNet sites such as Sunnyside received record rainfall of nearly 0.75 inches in only fifteen minutes! The overall impact was a reduction of the apple crop expectations, although a significant yield is still expected. Overall, July of 2012 was much warmer than its 2011 counterpart.

Other notable aspects of July's weather include hot and humid conditions during the second week of the month that were punctuated by temperatures as high as 107 degrees. July 8th was unique because parts of central Washington received a rare rainfall on a day with high temperatures in the 100s. A cool, wet June was highlighted by several unusual events. An all-time daily record rainfall of nearly 1.5 inches occurred on the 4th at Station 2, located in Benton County between Plymouth and Paterson, just across the Columbia River from Oregon. In addition, the high temperature was only 48 degrees at Pullman on June 9th. High temperatures were at least 3 degrees below normal for the month of June, and Prosser (WSU IAREC) had its second wettest June on record. Overall, temperatures were around average this summer, although there was significant weather pattern variability during the season. While June was cooler and wetter than normal, August was unusually hot and dry in most places. The trend of the last several years that has featured cool conditions in the late spring and early summer transitioning to warm conditions in the late summer and early autumn continued in 2012.

August weather can be characterized by three words: sunny, dry, and hot. One of the most notable events of this month was the August 4th heat wave that finally delivered hot temperatures to the entire state, including the coast. Despite temperatures as high as 107 degrees in July in central Washington, coastal areas did not experience adequate offshore flow to allow the heat to reach its full potential until August. Temperatures on the 4th were as high as 101 degrees in Vancouver, even though the heat was slightly less intense in eastern Washington relative to the July heat wave. Many locations recorded temperatures in the 90s, including Olympia, Montesano, and Long Beach. However, the coast quickly cooled down the following day. By August 7th, extreme heat had reached eastern Washington, as Pullman recorded temperatures in the upper 90s. Two notable days of record conditions occurred at Prosser (WSU IAREC) last month. The 6th was the warmest August day on record, and featured an average daily temperature of 83.8°F. The low temperature of 69.1°F on August 15th was also a monthly record warm value. Overall, August began with consistently hot weather, and ended with more seasonal temperatures.

In spite of the dearth of extreme heat, high temperatures in much of central Washington were much hotter than normal in August due to a lack of any cool day time weather for the first three weeks of the month. By contrast, low temperatures were only slightly above normal. Most locations did not record any below normal temperature days until August 22nd. The theme during the final ten days of the month was more seasonal weather. The other big August weather story was the lack of rainfall and the associated fires. Most AgWeatherNet locations received no rainfall during the month. Pullman's last rainfall occurred on June 30th, and its dry streak reached 62 days on August 31st, while Moxee's last rainfall occurred on July 14th.

August 2012 Average Temperatures (°F)
Location (Period of Record) Maximum Anomaly Minimum Anomaly Mean Anomaly Soil Temperature
8 inches
Prosser (WSU IAREC; 1989-2012)
89.1
2.6
54.4
0.3
71.7
1.6
75.0
Moxee (1989-2012)
89.8
3.2
48.5
0.2
69.3
1.8
74.3
Mt. Vernon (WSU NWREC; 1994-2012)
74.1
0.9
52.4
0.1
62.9
0.7
66.4
Wenatchee (WSU TFREC; 1994-2012)
90.7
3.6
60.3
2.0
75.7
2.8
80.7
Tri-Cities (1995-2012)
93.0
NA
58.1
NA
76.2
NA
84.9
Walla Walla (1993-2012)
90.0
3.8
57.8
-0.6
74.2
1.7
84.1
Moses Lake (1989-2012)
89.7
NA
55.4
NA
72.9
NA
80.5
Omak (Pogue Flat; 2005-2012)
88.9
NA
56.9
NA
73.2
NA
75.4
Royal City East (2008-2012)
86.3
NA
58.5
NA
71.9
NA
77.7
Pullman (2008-2012)
85.1
NA
44.1
NA
66.5
NA
71.4
Long Beach (WSU Long Beach; 2005-2012)
67.2
NA
51.3
NA
58.7
NA
62.8
Sequim (2008-2012)
72.3
NA
49.4
NA
61.1
NA
62.2
Seattle (2011-2012)
78.5
NA
55.4
NA
66.3
NA
69.8
Vancouver (WSU RE; 2008-2012)
81.3
NA
54.4
NA
67.6
NA
67.3
August 2012 Rainfall and Evapotranspiration (ET) (inches)
Location (Period of Record) Rainfall ET Net
(Rain - ET)
Prosser (WSU IAREC; 1989-2012)
0.05
9.17
-9.12
Moxee (1989-2012)
0.00
8.03
-8.03
Mt. Vernon (WSU NWREC; 1994-2012)
0.01
4.99
-4.98
Wenatchee (WSU TFREC; 1994-2012)
0.00
9.12
-9.12
Tri-Cities (1995-2012)
0.03
9.82
-9.79
Walla Walla (1993-2012)
0.00
9.16
-9.16
Moses Lake (1989-2012)
0.00
9.12
-9.12
Omak (Pogue Flat; 2005-2012)
0.00
7.98
-7.98
Royal City East (2008-2012)
0.00
8.11
-8.11
Pullman (2008-2012)
0.00
8.96
-8.96
Long Beach (WSU Long Beach; 2005-2012)
0.21
3.41
-3.20
Sequim (2008-2012)
0.01
4.42
-4.41
Seattle (2011-2012)
0.00
5.11
-5.11
Vancouver (WSU RE; 2008-2012)
0.00
6.25
-6.25

August Weather
Early August
August began with seasonal conditions that quickly transitioned to hot weather during the first weekend of the month. Offshore flow on the 4th caused what was by far the hottest weather of the year in much of western Washington, and especially at the coast. Highs were in the 90s in most places, including at the coast at Long Beach. It was the hottest weather at Vancouver since July 2009. Highs in eastern Washington were also very hot in the mid 90s to mid 100s. Sunday, August 5th was similar or even hotter than Saturday in some areas, although the coast experienced significant cooling and a return to more normal weather, as the flow turned back to onshore. More humid conditions entered the region overnight, which lead to very warm low temperatures. A few instability showers were triggered by a weak wave that passed through the region during the night and into the morning hours. However, very little thunderstorm activity occurred, and most of the rain was virga that did not reach the ground. The exception was a lone thunderstorm that dropped 0.17 inches of rain on Cowiche at around 3 pm on August 6th.

Interior western Washington remained above average but was less hot on Monday, August 6th. High temperatures as warm as 105.5°F occurred on the 6th east of the Cascades, while Vancouver was the hot spot in the west at 88.4°F. Low temperatures were as warm as 79 degrees in some areas. August 7th remained hot, with some 100s being recorded east of the Cascades, although all of western Washington finally experienced much cooler weather in the 70s and 60s. As the heat pushed eastward, Pullman reached a high in the upper 90s! Thereafter, dry weather continued, with somewhat above average temperatures continuing east of the Cascades. A variable, day to day temperature pattern persisted for western Washington, depending upon the degree of onshore flow.

Mid August
Hot weather returned for the weekend of the 11th and 12th, with 90s to around 100 in central Washington, and 80s in western Washington. Slightly cooler weather on the 13th and 14th was replaced with extreme heat on August 15th. Wahluke Slope's low temperature was above 80°F on the 13th, despite the presence of dry air, while Pullman and Sequim had lows in the 40s.

The most significant environmental concerns of the period were the active wildfires. The destructive Taylor Bridge Fire near Cle Elum burned nearly 24,000 acres, while other small fires also burned around the Northwest. Strong and dry high pressure that was entrenched over the region made for high fire danger, while abundant smoke caused poor air quality. Northerly offshore flow caused very dry and hot conditions, as gusty winds aggravated the fires and blanketed eastern Washington with smoke. Highs were in the 80s and 90s across the state on Wednesday the 15th. August 16th high temperatures ranged from 97°F at Vancouver to 70°F at Long Beach. Highs were in the 90s across much of western and central Washington, and in the 80s in eastern Washington around Pullman and Spokane.

Late August
Cooling that had arrived at the coast on the 16th reached the interior of western Washington on Saturday, August 18th. Cooler weather finally arrived in eastern Washington on the 21st, as a breezy cold front moved through the region. Highs fell into the 80s, while lows dropped into the 50s, as a cleaner air mass replaced the thick smoke over the region. The front also delivered the first appreciable rain to any part of the state in a month, though most areas remained dry. While generally light and isolated in nature, a few areas in eastern Washington received a tenth of an inch or more of rainfall on the 21st. In the parched August conditions, any rainfall and cool air was beneficial to the fire danger, although gusty winds and a few lightning strikes also accompanied the rain and thunderstorms.

By the 24th, some areas of eastern and central Washington recorded highs only in the 70s, while widespread areas saw lows in the 40s. Temperatures on the morning of the 24th fell below 39 degrees at East Olympia and Tumwater SW. The low at Pullman on the morning of the 25th was a chilly 32°F, which was its coldest temperature of the summer. Warmer weather staged a comeback for the 25th and 26th, before cooler weather returned from the 29th to the end of the month, as high fell into the 70s and 80s east of the Cascades, and 60s and 70s in western Washington. Pullman had another cool morning on the 30th, with a low of 35 degrees. All in all, August ended with typical late summer weather that featured warm, sunny days and cool nights in eastern Washington, and periods of clouds and sun in western Washington.

August 2012 Daily Temperatures
2012 Temperature Time Series Graph for Prosser 2012 Temperature Time Series Graph for Moxee
2012 Temperature Time Series Graph for Wenatchee 2012 Temperature Time Series Graph for Tri-Cities
2012 Temperature Time Series Graph for Walla Walla January 2012 Temperature Time Series Graph for WSU Pullman
January 2012 Temperature Time Series Graph for WSU Moses Lake January 2012 Temperature Time Series Graph for WSU Omak
January 2012 Temperature Time Series Graph for WSU Long Beach January 2012 Temperature Time Series Graph for WSU Mt. Vernon

August-By The Numbers
The average August temperature at Prosser (WSU IAREC) was 71.7°F, which is 1.6 degrees (1 standard deviation) above average. The average high temperature was 89.1°F, which is 2.6 degrees (1.4 standard deviations) above average, and is the second warmest on record. The average low temperature was 54.4°F, which is 0.3 degrees above average. The maximum temperature recorded last month was 100°F on August 6th, while the coolest daily high was 76.2°F on August 24th. Low temperatures ranged from 69.1°F on August 15th to 43.6 on August 24th. Daily average temperatures ranged from 83.8°F on the 6th to 60.1°F on the 24th. The monthly rainfall total was 0.05 inches. The average wind speed was 3.9 mph, and the average 8 inch soil temperature was 75.0°F. Other key sites around the state also observed above normal temperatures, including Wenatchee (WSU TFREC), whose average high temperature of 90.7°F was 3.6 degrees above average. Mt. Vernon's mean August temperature was 62.9°F, which is 0.7 degrees above average. Overall, this August was warmer than last August, and the average high temperature was slightly warmer than it was during July.


Notable August Events
  • August 4th: The temperature at Vancouver soared to 101 degrees.
  • August 4th: The temperature at Long Beach climbed to 94.3 degrees, after failing to reach 67 degrees during all of July.
  • August 15th: The low temperature at Prosser (WSU IAREC) fell to only 69.1 degrees, setting a record warm daily low for the month of August.
  • August 25th: The low temperature at Pullman fell to 32 degrees.

August Temperature Extremes (°F)
  Observed in 2012 Record Monthly Extremes
Site (Period of Record) Warmest Date Coldest Date Warmest Date Coldest Date
Prosser (WSU IAREC; 1989-2012)
100.0
8/6/2012
43.6
8/24/2012
102.2
8/14/1992
38.5
8/31/2008
Moxee (1989-2012)
99.2
8/6/2012
38.1
8/25/2012
102.8
8/1/2009
NA
NA
Mt. Vernon (WSU NWREC; 1994-2012)
87.0
8/17/2012
44.1
8/31/2012
89.8
8/29/1996
40.6
8/28/2010
Wenatchee (WSU TFREC; 1994-2012)
100.4
8/7/2012
46.7
8/25/2012
106.4
8/17/2008
42.2
8/28/2000
Tri-Cities (1995-2012)
105.2
8/7/2012
45.5
8/25/2012
106.8
8/4/1998
46.0
8/31/2008
Walla Walla (1992-2012)
100.3
8/6/2012
44.1
8/25/2012
106.1
8/4/1998
42.2
8/4/1992
Moses Lake (1989-2012)
101.4
8/7/2012
44.2
8/25/2012
104.7
8/4/1998
NA
NA
Omak (Pogue Flat; 2005-2012)
98.0
8/5/2012
44.5
8/30/2012
104.0
8/17/2012
40.2
8/31/2006
Royal City East (2008-2012)
95.3
8/13/2012
47.6
8/24/2012
101.4
8/17/2008
42.9
8/31/2008
Pullman (2008-2012)
97.9
8/7/2012
32.0
8/25/2012
102.2
8/17/2008
32.0
8/25/2012
Long Beach (WSU Long Beach; 2005-2012)
94.3
8/4/2012
42.7
8/25/2012
94.7
8/14/2010
39.5
8/31/2010
Sequim (2008-2012)
85.6
8/15/2012
38.4
8/25/2012
87.0
8/15/2010
36.4
8/23/2010
Seattle (2011-2012)
95.0
8/16/2012
48.2
8/25/2012
NA
NA
NA
NA
Vancouver (WSU RE; 2008-2012)
100.6
8/4/2012
42.9
8/24/2012
100.6
8/4/2012
40.1
8/31/2008

Summer Weather
June and July Review
The weather in June was cooler and wetter than average, while July conditions were slightly warmer and stormier than normal. June day-time temperatures were generally 3 or more degrees below average across Washington, while overnight lows were only slightly below average. Overall, Prosser (WSU IAREC) recorded the coolest June since 2001, and the second wettest June on record (1989 to present). Pullman climbed to only 48 degrees on June 9th, and Ritzville dropped to a frosty 31.7 degrees on June 15th. Station 2, located in Benton County, between Plymouth and Paterson, just across the Columbia River from Oregon, recorded an all-time daily record 1.46 inches rain on June 4th.

July temperatures were slightly above average east of the Cascades, and slightly below average in western Washington. July began with cool conditions that quickly transitioned to hot weather after the 4th of July. The subsequent heat wave brought temperatures as warm as 107.3 degrees, along with a record high temperature at Sunnyside of 104 degrees. July 8th featured an unusual combination of extreme heat and thunderstorms in the Yakima area. Some areas received significant rainfall after experiencing afternoon highs in the 100s, making it the hottest day with rainfall on record in places such as Mattawa. The middle part of the July was stormy and humid, as Washington recorded thunderstorms each day from the 14th to the 20th. Certain AgWeatherNet sites recorded heavy rainfall of around 0.75 inches in only fifteen minutes during strong thunderstorms. The culmination of the active weather was a severe weather outbreak on the 20th that led to isolated, devastating hail-induced crop damage. More seasonal weather occurred at the end of July. Overall, July rainfall was above normal but highly variable due to the convective nature of the month.

summer 2012 Daily Rainfall Time Series Graph for Prosser summer 2012 Daily Rainfall Time Series Graph for Long Beach

Summer-By The Numbers
The average summer temperature at Prosser (WSU IAREC) was 69.4°F, which is nearly normal (0.1 degrees above average). The hot August conditions served to balance the cool weather during June. The average high temperature was 84.5°F, which is 0.2 degrees above average, while the average low temperature was 53.4°F, which is only slightly (0.4 degrees) above average. Daily high temperatures ranged from 101.2°F on July 8th to 60.8°F on June 4th. Low temperatures varied from 69.1°F on August 15th to 39.2°F on June 9th. Daily average temperatures ranged from 83.8°F on August 6th to 53.3°F on June 8th. 1.97 inches of rain fell during the summer season. The average wind speed was 4.3 mph, while the average 8 inch soil temperature was 73.1°F. Other locations also experienced near to slightly above normal summer temperatures. Wenatchee (WSU TFREC) had an average summer temperature of 72.1°F, which is 0.6 degrees above average. An exception was Mt. Vernon (WSU NWREC) in western Washington, whose average summer temperature of 59.9°F was 1 degree below average, due to a cool June and July. Overall, the summer of 2012 was nearly 2 degrees warmer than the summer of 2011.

Summer 2012 Average Temperatures (°F)
Location (Period of Record) Maximum Anomaly Minimum Anomaly Mean Anomaly Soil Temperature
8 inches
Prosser (WSU IAREC; 1989-2012)
84.5
0.2
53.4
0.4
69.4
0.1
73.1
Moxee (1989-2012)
84.7
NA
48.5
NA
67.5
0.4
70.8
Mt. Vernon (WSU NWREC; 1994-2012)
69.5
NA
51.2
NA
59.9
-1.0
64.4
Wenatchee (WSU TFREC; 1994-2012)
85.1
0.5
58.3
1.0
72.1
0.6
76.4
Tri-Cities (1995-2012)
87.7
NA
56.6
NA
72.9
NA
80.5
Walla Walla (1993-2012)
84.0
0.7
56.3
-0.6
70.3
0.0
78.1
Moses Lake (1989-2012)
84.2
NA
54.5
NA
69.7
NA
75.7
Omak (Pogue Flat; 2005-2012)
83.5
NA
55.3
NA
69.8
NA
70.1
Royal City East (2008-2012)
82.1
NA
56.1
NA
68.9
NA
74.0
Pullman (2008-2012)
78.4
NA
46.7
NA
63.6
NA
68.0
Long Beach (WSU Long Beach; 2005-2012)
63.5
NA
49.9
NA
56.7
NA
61.7
Sequim (2008-2012)
67.0
NA
48.1
NA
57.9
NA
59.5
Seattle (2011-2012)
72.8
NA
53.8
NA
62.8
NA
66.7
Vancouver (WSU RE; 2008-2012)
75.4
NA
53.2
NA
64.1
NA
66.3
Summer 2012 Rainfall and Evapotranspiration (ET) (inches)
Location (Period of Record) Rainfall ET Net
(Rain - ET)
Prosser (WSU IAREC; 1989-2012)
1.97
26.25
-24.28
Moxee (1989-2012)
1.42
24.05
-22.63
Mt. Vernon (WSU NWREC; 1994-2012)
4.46
13.62
-9.16
Wenatchee (WSU TFREC; 1994-2012)
0.95
26.08
-25.13
Tri-Cities (1995-2012)
1.97
27.66
-25.69
Walla Walla (1993-2012)
3.73
24.78
-21.05
Moses Lake (1989-2012)
2.65
25.54
-22.89
Omak (Pogue Flat; 2005-2012)
3.74
22.72
-18.98
Royal City East (2008-2012)
3.09
23.95
-20.86
Pullman (2008-2012)
1.69
23.83
-22.14
Long Beach (WSU Long Beach; 2005-2012)
4.47
7.50
-3.03
Sequim (2008-2012)
2.33
9.40
-7.07
Seattle (2011-2012)
4.04
14.10
-10.06
Vancouver (WSU RE; 2008-2012)
3.44
15.15
-11.71
Notable Summer Weather Events
  • June 9th: The high temperature at Pullman was only 48.4 degrees.
  • June 15th: The low temperature at Ritzville fell to 31.7 degrees.
  • June 26th: 1.2 inches of rain fell at Davenport.
  • July 8th: The temperature at Mesa SE climbed to 107.3 degrees.
  • July 15th: 2.3 inches of rain fell at Malott, including 1.25 inches in 30 minutes.
  • July 20th: 0.73 inches of rain fell at Sunnyside in only 15 minutes during a severe thunderstorm.
  • August 6th: The average daily temperature at Prosser (WSU IAREC) was a toasty 83.8°F, which was its warmest August day on record.
Summer 2012 Temperature Extremes (°F)
  Observed in 2012 Record Seasonal Extremes
Site (Period of Record) Warmest Date Coldest Date Warmest Date Coldest Date
Prosser (WSU IAREC; 1989-2012)
101.2
7/8/2012
39.2
6/9/2012
109.9
7/12/2002
35.3
6/6/1999
Moxee (1989-2012)
101.0
7/8/2012
35.6
6/8/2012
107.5
7/12/2002
29.2
6/6/1999
Mt. Vernon (WSU NWREC; 1994-2012)
87.0
8/17/2012
40.0
6/15/2012
96.1
7/29/2009
40.0
6/2/1999
Wenatchee (WSU TFREC; 1994-2012)
102.6
7/8/2012
40.0
6/8/2012
106.6
7/23/2006
40.0
6/8/2012
Tri-Cities (1995-2012)
106.3
7/8/2012
43.9
6/15/2012
110.1
7/23/2006
40.9
6/2/2001
Walla Walla (1992-2012)
100.9
7/8/2012
43.7
6/7/2012
107.3
7/12/2002
37.9
6/7/1995
Moses Lake (1989-2012)
101.4
8/7/2012
38.8
6/7/2012
107.8
7/23/2006
37.8
6/8/2002
Omak (Pogue Flat; 2005-2012)
101.6
7/8/2012
35.4
6/7/2012
105.5
7/23/2006
35.4
6/7/2012
Royal City East (2008-2012)
99.4
7/9/2012
41.5
6/9/2012
101.4
8/17/2008
40.3
6/16/2010
Pullman (2008-2012)
97.9
8/7/2012
32.0
8/25/2012
102.2
8/17/2008
31.2
7/11/2008
Long Beach (WSU Long Beach; 2005-2012)
94.3
8/4/2012
37.9
6/6/2012
95.5
7/7/2010
36.9
6/12/2007
Sequim (2008-2012)
85.6
8/15/2012
33.5
6/15/2012
91.8
7/28/2009
32.8
6/30/2009
Seattle (2011-2012)
95.0
8/16/2012
43.5
6/15/2012
NA
NA
NA
NA
Vancouver (WSU RE; 2008-2012)
100.6
8/4/2012
39.6
6/6/2012
104.1
7/29/2009
39.6
6/6/2012

Weather Summary By Month
  • June: Cool and wet.
  • July: Stormy and warm.
  • August: Hot and dry.

Agriculture Report
A larger than normal portion of the cherry crop remained unharvested as of the end of August in Chelan County. Harvest continued of late maturing varieties of peaches, nectarines and Bartlett pears, while Gala apple harvest began in the warm sections of Yakima County. Hop harvest activity also began in the Yakima Valley. Winter wheat harvest was being completed in Lincoln County, while 30% of the spring wheat remained in the fields. Wheat yields were average in Grant and Ferry Counties. In Grays Harbor County, raspberry harvest finished while blueberry and cannery pea harvest reached its peak. Christmas tree growers in western Washington continued top working and side shearing the fir trees (National Agricultural Statistics Service).

April 1 to August 31 Accumulated Growing Degree Days
  Base Temperature (°F)
32 43 50
Location 2012 5 Year Avg Difference 2012 5 Year Avg Difference 2012 5 Year Avg Difference
Prosser (WSU IAREC)
4817
4639
178
3136
2965
171
2120
1981
139
Tri-Cities
5228
5124
104
3545
3444
101
2507
2422
85
Walla Walla
4943
4784
159
3262
3107
155
2228
2110
118
Wenatchee (WSU TFREC)
5089
4940
149
3407
3266
141
2385
2273
112
Moxee
4445
4154
291
2775
2517
258
1807
1603
204
Omak (Pogue Flat)
4778
4645
133
3102
2983
119
2122
2030
92
Moses Lake
4817
4697
120
3139
3027
112
2128
2044
84
Pullman
3873
3667
206
2224
2057
167
1328
1209
119
Royal City East
4810
4668
142
3128
2995
133
2112
2017
95
Mt. Vernon (WSU NWREC)
3814
3696
118
2131
2020
111
1119
1051
68
Long Beach (WSU Long Beach)
3309
3284
25
1633
1614
19
689
699
-10

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 August 17th, 2008, the temperature at Wenatchee (WSU TFREC) climbed to a monthly record 106.4 degrees!

Climate Outlook
According to the Climate Prediction Center (CPC), drier than normal conditions are expected in September, especially in western Washington, along with near normal temperatures. These trends are likely to continue for the rest of the autumn, with warmer than normal conditions possible by the winter of 2012/2013. El Niño conditions will soon develop, and should persist through the winter, which suggest that a mild and benign winter is more likely this year.

Washington State University