Thunderstorm-related precipitation late in the month also helped to maintain the higher river levels. The Grande Ronde River also experienced minor flood conditions during the month. Wet-season snowpack accumulation and precipitation are still expected to provide ample streamflows this summer in all basins. Most basins are still in the moderately moist category. The Harney and Umatilla basins have the lowest values in the interior and they are in the slightly moist category.
Coastal areas are also in the slightly moist category.
May temperatures were well above average statewide. Monthly temperatures were generally four to six degrees above average. This was the 2nd warmest May on record at Portland. May began with some record low temperatures in northeast Oregon. The air warmed in a hurry, though, with maximum temperatures soaring to 20-30 degrees above average during the second week of the month.