The overnight low in Washington was 84 degrees, while the coolest the heat index got was 90. DC's all-time warm low of 84, on three prior dates, was last hit in 2011. As long as no storms knock readings back before midnight, 2026 will be added to the list with another night of extreme warmth ahead.
Dulles sneaked a 78 despite hourly observations never falling below 80, while BWI Marshall fell to 79. Both will be new records for the date.
Lows that were closer to average highs stretched to New York City and Boston. The former only dipped to 84, while the latter made it to 82. NYC's record prior to today is 84, while Boston's is 83.
DC has seen a major increase in lows of 80 or higher over recent decades. Since 2000, 48 days (not including Friday, yet) have seen lows of 80 or higher. From 1872 to 1999 there were 26. It is among the clearer signs of climate change in our region.
An extreme heat warning is in place today in and around DC for heat index 110-plus and highs about 100 to 105. More of the same through tomorrow.
