WASHINGTON — A dangerous heat wave expanded across broad areas of the United States on Monday, with the National Weather Service warning that prolonged high temperatures and oppressive humidity would create hazardous conditions for tens of millions of people across parts of the Midwest, Great Lakes, Plains, South and East as the week begins.
Forecasters said a strong high-pressure system, commonly referred to as a heat dome, was driving temperatures into the upper 90s and low 100s degrees Fahrenheit across many locations, while high humidity was expected to push heat index values well above air temperatures. Some areas could experience heat index readings as high as 115 degrees Fahrenheit, according to National Weather Service forecasts.
The National Weather Service issued or maintained heat-related watches, advisories and warnings for numerous states, urging residents to limit strenuous outdoor activity, stay hydrated and seek air-conditioned shelter. Meteorologists also warned that unusually warm overnight temperatures would provide little relief, increasing the risk of heat-related illness, particularly for older adults, young children, outdoor workers and people without access to cooling.
Forecasts indicated that several major metropolitan areas, including Chicago, New York, Philadelphia and Washington, D.C., could approach or exceed daily temperature records later in the week as the heat spread eastward. Officials also cautioned that hot, dry conditions in parts of the western United States were contributing to elevated wildfire danger.
The Weather Prediction Center said the heat wave was expected to remain a significant national weather hazard over the coming days, while local forecasts and alerts continued to be updated as conditions evolved. Authorities said additional warnings could be issued as the event develops.
