Western Regional Climate Center


July in the West

Temperatures throughout the region were near normal with the northern half slightly below normal and the southern half slightly above. Coastal California had some very low average maximum temperatures due to a persistent marine layer all month. Downtown San Francisco had its coolest average July maximum temperature (63.1 deg F, 17.3 C) since 1971. San Diego’s monthly average of 65.9 F (18.8 C) was the coolest July since 1933.

Most of the west measured below normal rainfall except for parts of the southwest and eastern Montana. Although the southwest monsoon started about a week later than usual it made up for it quickly with heavy rain during the latter half of the month. Flagstaff measured 5.94 inches of rain making it the third wettest July dating back to 1924. Cloudcroft, New Mexico, measured 12.21 inches (310 mm) making it the second wettest July on record dating back to 1902.

Significant Events for July 2010

July 1: Hailstorm in Montana: Although the hailstorm occurred on June 30th in the Bozeman area, the damage was not determined until the following day. Damage from the golf ball to tennis ball sized hail was estimated to be $60 million in Bozeman.

July 20: Mudflows in Arizona: Heavy rain over the San Francisco Peaks near Flagstaff fell on the area burned last month in the Schultz Fire causing large mudflows and killing one 12 year old girl who fell into a flooded wash. Water, mud and ash covered roads and inundated numerous homes in the area.

July 21: Lightning in Grand Tetons, Wyoming: Sixteen climbers were rescued over an eight hour rescue operation after they became injured by a midday thunderstorm. Eight of the climbers were treated for injuries sustained by nearby lightning and one person died falling off a cliff.

July 22-23: Flooding in eastern Alaska: Heavy rain fell over the Forty Mile River Basin in eastern Interior Alaska causing numerous washouts, mudslides and slumping road beds along the Taylor Highways from Chicken to Eagle.

July 26: Tornado in Northeastern Montana: Supercells in northeast Montana spawned one tornado, three inch hail and 70 mph winds. A 10-year old boy and his 46-year old uncle were killed by the tornado (later rated an EF3) near Reserve, MT. Nearly 6 miles of power lines were downed. This tornado was rated one of the strongest and the most deadly in Montana history and the strongest tornado to hit the state since 1988.

July Fires: Numerous fires burned in the west but the most significant were those in California where numerous homes were destroyed. The West Fire near Tehachapi began on the 27th and within 12 hours more than 20 homes had been lost with another 150 structures threatened. By the end of July a total of 25 homes had been destroyed and over 1,400 acres burned. In northern Kern County the Bull Fire, which began on the 26th, had burned more than 16,000 acres by the end of the month with roughly 85% containment. This fire had destroyed 8 residences. Between these two fires over 2,300 people in the area had been evacuated.

July 2010 Departure from Normal Temperature and Percent of Normal Precipitation for Western United States

Departure from normal temperature Departure from normal precipitation

© Western Regional Climate Center