The hottest day: 106 degrees. It happened twice. On July 20, 1930, during a long nationwide drought, the humidity was low (30 percent) so few people died of heat prostration, but it was very dry and at Washington Cathedral prayer was offered for rain. On Aug. 6, 1918, the heat was combined with high humidity, and the city virtually shut down. The city didn't cool off at night and the day set a record for the highest average temperature -- 92 degrees. Those who couldn't escape the city took pillows to city parks and slept. A thermometer in the courthouse reached 121 degrees.
The hottest summer: 1980. The summer set all kinds of records for continuous miserable weather. Twenty-one straight days of 90 degrees or higher temperatures. The hottest July (82.3 record monthly maximum average, 73.6 record minimum monthly average), hottest August (92 record monthly maximum average, 82.8 record monthly mean temperature, 73.8 record minimum monthly average) and highest average temperature for June, July and August -- 80 degrees. The hottest day of that summer was 103 degrees, the hottest day in 37 years.
The wettest summer day. During a 24-hour period on Aug. 11 and 12, 1928, 7.31 inches of rain fell.
The worst thunderstorm. On July 30, 1918, a thunderstorm hit only the District, leaving Maryland and Virginia untouched. It exploded at 3 p.m. with 70-mile-an-hour winds, dumping 2.02 inches of rain in less than 15 minutes, battering the city with hail, ripping off hundreds of roofs and killing two people when a building collapsed.
The hottest spell. The worst hot spell occurred from Aug. 5 to Aug. 9, 1918, with an average temperature of 99.6 degrees.
From the National Weather Service, based on continuous records from 1870.