May was one of warmest on record With hail, high water and many tornadoes touching down, the start of this month was filled with meteorological drama. But last month's weather in Washington also was exceptional. May was uncommonly warm. With an average high temperature of 71.4 degrees, May was the fourth-warmest here since the National Weather Service began keeping records in 1871. It also was the seventh successive month during which Washington's temperature was above average. The last month with a temperature below average was October. The temperature at Reagan National Airport last month was 5.4 degrees above normal. Only two 90-degree days contributed to the achievement of that mark. On May 28, the mercury at the airport reached 90 for the first time this year. The next day, the high reading was 91. Otherwise, the month's high temperatures were all in the 70s and 80s. Only two days saw temperatures that were below average. Meanwhile, there were 25 days in May with a high temperature of at least 75. That was the high temperature recorded at the airport Monday. Although Friday, with its storminess, was warmer than average, Saturday, Sunday and Monday all were below average for their dates, making the overall average so far for June 1.5 degrees below normal.