July in the West
July was much wetter than normal in much of California and the Great Basin. Scattered areas of the Southwest and Intermountain West also experienced above normal precipitation. Temperatures along the coast and in the Pacific Northwest were well above normal for July, while inland areas were slightly cooler than normal. Washington and western Oregon were particularly warm and dry, exacerbating drought conditions.
July is typically one of the driest months of the year in southern California. This time, however, over the period of July 18-20, the remnants of Hurricane Dolores combined with a low-pressure system to produce record rainfall in the region. Paso Robles received 2.17 in (55 mm) for the month, the wettest July on record and 3.7 times more rainfall than the previous record of 0.59 in (15 mm) set in 1950. Records for Paso Robles began in 1948. San Diego airport also experienced its wettest July on record at 1.71 in (43 mm). This is more than 7 times the previous July record of 0.24 in (6 mm) in 1991 and 57 times the July normal of 0.03 in (<1 mm). This San Diego record began in 1939. July precipitation in the Great Basin and scattered areas of the Southwest was above normal as well, tied to a slow moving low-pressure system that helped to initiate thunderstorms across the region July 7-9th. Urban flash flooding was reported in several locations including Reno, Nevada and Boise, Idaho. Fallon, in northwestern Nevada, had its second wettest July in a 71-year record at 1.2 in (30 mm), 545% of normal. Over half of this fell on July 9. Further north, Boise, Idaho received 0.97 in (25 mm) for the month, 293% of normal, the 4th wettest July since records began in 1940. Albuquerque, New Mexico recorded 3.28 in (83 mm) of precipitation, 1.82 in (46 mm) of which fell on the 7th. Their July total was 219% of normal and the 7th wettest in a 119-year record. A large area of western Colorado and Wyoming saw drought improvement this month along with small areas of Arizona, western New Mexico, northern Nevada, eastern California, and north-central Montana. The rains received in California, especially in the south, though beneficial and significant for the season, were relatively small in quantity and did little to alleviate severe and persistent drought conditions for the state as a whole.
July marks the third consecutive month of widespread above normal temperatures in the Pacific Northwest. Seattle, Washington experienced its warmest July on record with an average 71.2 F (21.8 C), 5.5 F (3 C) above normal; last month was Seattle’s warmest June. In central Washington, Wenatchee had its second warmest July on record at 80.3 F (26.8 C), 6.1 F (3.4 C) above normal. In eastern Washington, Yakima had its third warmest July on record at 77.1 F (25.1 C). July 2013, 2014, and 2014 take the top three hottest Julys in Yakima’s 70-year record. Further south, Portland, Oregon saw its second warmest July on record with an average 73.9 F (23.3 C), 4.7 F (2.6 C) above normal. Portland also tied for second longest run of consecutive days with temperatures at least 90 F (32.2 C), at 8 days spanning June 19-July 6. The longest streak on record is 10 days, July 25-August 3, 2009. In southwestern Oregon, Roseburg had its warmest July on record at 76.1 F (24.5 C), 5.8 F (3.2 C) above normal. Roseburg also tied for its second and third all-time high temperatures this month at 108 F (42.2 C) on July 30 and 107 F (41.7 C) on July 31. Drier than normal conditions accompanied the warm temperatures in the Pacific Northwest. Walla Walla, in southeast Washington and North Bend in western Oregon recorded 0.04 in (1 mm) and 0 in. rainfall this month. These locations typically receive around 0.5 in (13 mm) in July. The warm and dry conditions this month aided in expansion and intensification of drought conditions throughout Washington and in western Oregon. Above normal temperatures were also observed in some coastal areas of California. In the southern part of the state, Santa Maria had its warmest July since this record began in 1948 at 68.6 F (20.3 C), 5.4 F (13 C) above normal. Along the northern coast, Arcata saw its warmest July at 60.2 F (50.7 C), 4.2 C (2.3 C) above normal.
Precipitation was variable across Alaska, with below normal values observed across the northern tier of the state and above normal values in the southeast. Juneau recorded 10.4 in (264 mm) for the month, 226% of normal and narrowly eclipsing the 1997 record wettest July in a 80 year record. Anchorage had its 3rd wettest July on record with 3.31 in (84 mm), including its wettest July day on record of 1.13 in (29 mm) on the 25th. Precipitation was generally below normal across Hawaii and temperatures above normal. Honolulu experienced its warmest July on record at an average 83.3 F (28.5 C), 2.1 F (1.2 C) above normal. Records for Honolulu began in 1940.
Significant Events for July 2015
**July (all month): Fires in Alaska: Over 700 wildfires in Alaska have burned nearly 5 million acres (2 million hectares) this summer. Approximately 300 of these fires have been human-caused, the rest by lightning. Late July rains helped to slow fire progress, though this season still has the potential to exceed the record set in 2004 of 6.59 million acres (2.6 million hectares) burned.
**July (all month): Fires in the West: More than a dozen large wildfires were burning in California at month’s end. One of the largest is the Rocky Fire in Lake County, northern California. The fire has reached 18,000 acres (7,300 hectares) and destroyed 3 homes. The California governor has declared a state of emergency to free up resources to fight the fires. Washington has also had many large wildfires this month. One of the largest is the Douglas County Complex fire that has burned over 22,000 acres (8,900 hectares) in the central part of the state since it was ignited by lightning on July 10.