By STACY LIBERATORE, US SCIENCE & TECHNOLOGY EDITOR
Published: 13:22 BST, 6 August 2026 | Updated: 14:24 BST, 6 August 2026
Emergency plans have been activated for millions as brutal heat and severe storms threaten to unleash dangerous flash flooding.
New York City Mayor Zohran Mamdani ordered the citywide response Thursday as all five boroughs entered a heat advisory lasting through 8pm Friday.
Similar heat alerts stretch across parts of Connecticut, New Jersey, Pennsylvania, Delaware, Maryland, Massachusetts and New Hampshire, as well as Washington DC.
The National Weather Service (NWS) warned that the heat index could reach around 100°F in New York City, 103°F across parts of Pennsylvania, New Jersey and Delaware and more than 105°F in southern Connecticut.
Overnight temperatures are expected to remain in the low 70s, offering little relief before the oppressive heat returns Friday.
The extreme conditions will coincide with thunderstorms capable of unleashing torrential rain, powerful winds and frequent lightning across the Northeast and Mid-Atlantic.
Forecasters warned that the storms could trigger localized flash flooding, topple trees and bring down power lines through Friday.
New Yorkers living in basement apartments were issued the most urgent warning and told to identify somewhere safer to shelter before floodwaters begin rising.
New York City Mayor Zohran Mamdani ordered the citywide response Thursday as all five boroughs entered a heat advisory lasting through 8pm Friday
New York City officials urged residents to remain indoors during severe weather and avoid flooded roads.
The most urgent warning was issued to people living in basement apartments, who were told to identify somewhere safer to shelter before floodwaters begin rising.
Anyone trapped or facing immediate danger should call 911, while downed trees, clogged catch basins and other nonemergency hazards can be reported to 311.
'City government is mobilizing every resource we have – from clearing catch basins and preparing emergency crews to sending COOL vans to check on older adults,' Mamdani said.
