WASHINGTON — High temperatures combined with elevated humidity prompted widespread heat advisories across large parts of the eastern and central United States on Thursday and Friday, with officials warning of dangerous conditions that could lead to heat-related illnesses.
The National Weather Service issued heat advisories for regions including the Northeast, Mid-Atlantic, Midwest and parts of the South, where heat index values — a measure combining temperature and humidity — were forecast to reach 100 to 110 degrees Fahrenheit or higher in many locations.
Conditions were expected to peak on June 11 and 12, 2026, affecting tens of millions of people. Heat advisories covered areas such as New York City, New Jersey, Pennsylvania, parts of Maryland and the Midwest, with some locations seeing heat indices approaching or exceeding 105 degrees.
Officials urged residents to limit outdoor activity, stay hydrated and check on vulnerable populations, including the elderly, children and those with chronic health conditions. Air conditioning or cooling centers were recommended for those without adequate home cooling.
"Heat indices near 100 degrees are expected," local weather service statements indicated regarding the combination of temperatures in the upper 80s to low 90s and high humidity.
The heat dome pattern, characterized by high pressure trapping warm, moist air, has driven the elevated risks this week. Some areas could see record or near-record highs for mid-June, with overnight lows offering limited relief due to humidity.
Vulnerable groups face heightened risks of heat exhaustion and heat stroke. Emergency management officials in affected states activated extreme heat protocols, with some school districts adjusting schedules. Details on the total number of people under alerts varied by region as conditions evolved.
In the Northeast, cities such as New York and Philadelphia were among those under advisory, with potential for heat indices up to 110-115 degrees in spots. Similar warnings extended into the South and central states.
As of Friday, forecasters anticipated gradual relief in some areas over the weekend with a shift in weather patterns bringing slightly cooler and drier air. The National Weather Service continued to monitor conditions and update advisories accordingly.
Residents were advised to follow local guidance and prepare for continued warm and humid conditions in the near term. Further updates on the duration and intensity of the heat were expected as the system progressed.
