When temperatures climb into the triple digits, D.C. faces a different level of heat. Days in the 90s can be sweltering — especially when humidity is high — but conditions turn particularly brutal once the mercury crosses the century mark.
Days at or above 100 degrees are rare compared with the many summer afternoons that top out in the 90s. On average, the city sees about one such day per year — and many years pass with none at all.
Still, when they do occur, they can be memorable. The hottest temperature ever recorded in D.C. is 106 degrees, reached Aug. 6, 1918, and again July 20, 1930. More recently, the mercury hit 105 degrees on July 7, 2012, and reached 104 degrees on July 16, 2024.
100-degree days annually
D.C. averages just over one day per year at or above 100 degrees, but these extremes don’t usually show up every summer. Instead, they tend to arrive in bursts during particularly intense heat waves.
For example, six triple-digit days occurred in 2024. Before that, the city hadn’t seen any since 2016, when four such days were recorded.
The record for a single year is 11 days of 100-degree heat, set in 1930. More recently, 2012 delivered eight — the second-highest total on record.
Longest streaks of 100-degree days
Triple-digit heat in D.C. can occasionally linger for several days in a row during the most intense heat waves. The longest such streak on record is four consecutive days at or above 100 degrees.
Most recently, that happened in 2024, when the temperature reached the century mark from July 14 to 17. The four-day run tied the longest streak previously observed in the city, matching similar stretches during the notorious heat waves of 2012 and 1930.
When 100-degree days happen most often
Triple-digit heat in D.C. is largely confined to the heart of summer. The earliest 100-degree reading on record occurred June 5, 1925, when the temperature hit exactly 100 degrees. The latest came Sept. 8, 1939 — also right on the century mark.
Most 100-degree days cluster around late July, which is typically the hottest stretch of the year in the city. In fact, July 21 stands out as the single most common date for temperatures to reach at least 100 degrees. Across the historical record, the core window for repeated triple-digit heat runs from June 29 through July 23.
