May ended with a flourish of sunny, 80-plus degree days — not unexpected for a month that was warmer than normal.
Daytime highs averaged 74.2 degrees, a mark 3.8 degrees above normal, and nighttime lows averaged 51.5 degrees, which was 3.2 degrees above average.
The warmest day came on May 11, when the high was 85 degrees, while the coolest night was on May 1, when the mercury sank to 38 degrees.
A 16-day dry spell, which began April 28, ended as a series of rainstorms moved in on May 14. The heaviest downpour fell on May 17, when 0.83 inches was recorded at Walla Walla Regional Airport.
The mid-month rainfall resulted in May finishing only slightly below normal for precipitation, with 1.95 inches total, a mark 0.18 inches below normal. Measurable rainfall, at least 0.01 inch, fell on 10 days, according to the National Weather Service.
Total rain and snow for this year is now at 10.45 inches, which is 0.19 inches below average. Since October, the water-year precipitation at Walla Walla is now 15.81 inches, which is 1.85 inches below normal.
The highest wind gust, 33 mph, came on May 9, as measured at Walla Walla Regional Airport.
The summer equinox on June 21 will mark the transition from spring into summer. According to the federal Climate Prediction Center, the outlook for June calls for normal temperatures and near-normal rainfall.
Normal highs for Walla Walla rise from 75 degrees at the start of June to 84 degrees by July 1. Normal lows rise from 52 degrees to 57 degrees. Normal rainfall is 1.28 inches based on a 30-year average.