May in the West
Temperatures throughout the west ranged from 2-4 deg F (4-7 deg C) below normal in the intermountain region and parts of the southwest to 2-4 deg F (4-7 deg C) above normal in parts of California and the northwest. Temperatures fluctuated widely throughout the region for the month. Record setting heat from the 17-20th gave way to record cold a few days later in many portions of the west. Las Vegas, NV, reported a high temperature of 108F (42C) on the 19th, a new record for the date. Four days later, May 23rd, the high temperature was 67F (19C), a new record low maximum for the date. Death Valley, CA, recorded their earliest 120F (49C) reading ever on May 19th, while Seattle recorded their earliest 90F (32C) reading ever on the 17th. Astoria, OR, reached 93F (34C) on the 16th setting a new maximum temperature record for May. The first week of the month broke all time low temperature records for May in numerous locations including Burns, OR, with 13F (-11C) on the 1st and Pueblo, CO, with 24F (-4C) on the 3rd.
Precipitation was a mixed bag as well. Portions of Wyoming and Montana recorded an extremely wet month while the Pacific northwest and California were quite dry. Lander, WY, measured 6.13 in (156 mm) of precipitation breaking their all time May record. Some of the highest elevations of Wyoming and Montana actually had their snow pack increase from May 1st to June 1st. Flagstaff, AZ, recorded their snowiest May ever with 8.7 in (22 cm). San Francisco had no measurable rain in May leading to their driest spring total (March-May) ever, 0.47 in (12 mm). Normally San Francisco receives 24% of their annual rainfall during these three months. This year, only 3% of their seasonal total fell during the 3 months. Although most of California was dry, an unusual event on the 23rd produced locally heavy rain in the mountains of southern California leading to local flash flooding, mudslides and road closures. Over 2 inches (51 mm) fell in some locations in the morning hours of the 23rd. Bakersfield measured .08 in (2 mm) on the 23rd breaking an 87-day period with no measurable rain. On June 4th, the governor of California signed an Executive Order proclaiming a statewide drought after two consecutive winters of dismal precipitation totals.
May 2008 Percent of Normal Precipitation and Average Temperature Departure.