Usually when we talk about flirting with record highs this time of year, the bar is set pretty high. 98, 99, often the the low 100s is what it takes to tie or set a record. It just so happens that tomorrow's date, July 24, carries the month's lowest record high temperature for Washington, D.C. -- 96 in 1987 (and at least one other previous year). With highs tomorrow expected to easily reach the upper 90s, and probably near 100 or into the low 100s, it seems fairly certain that we'll break that record.
After July 24th's 96 degrees, the next lowest record high is 99, which is the highest temperature recorded on July 11, 12, 29 and 30. The highest temperature on record for any date in D.C.? 106 on July 20, 1930, and on Aug. 6, 1918.
Interested in more historical D.C. area weather info? You can browse through National Weather Service data here.