The National Weather Service (NWS) warned on Sunday that a prolonged and hazardous heatwave is set to impact a vast portion of the central and eastern United States. As temperatures climb ahead of the Fourth of July holiday, high humidity levels are expected to significantly increase the perceived heat.
Parts of the Southwest, including central Texas and Phoenix, already experienced temperatures reaching 100F (38C) on Sunday. Simultaneously, the NWS issued warnings regarding severe wildfire risks across much of the West as new fires continue to emerge.
According to NWS data, more than 130 million Americans in the southern and Great Plains regions are currently under moderate to severe heat risks. This area is projected to expand as temperatures intensify throughout the week.
Meteorologists forecast that several days of extreme heat—with some temperatures exceeding 100F—will settle over the Mississippi and Ohio River valleys, the mid-Atlantic, and the lower Great Lakes. NWS meteorologist Bryan Putnam noted that record-breaking highs could be reached in parts of the mid-Atlantic and New England later this week.
Major metropolitan areas are expected to see their highest temperatures of the year, coinciding with World Cup matches and celebrations for the United States’ 250th anniversary.
Affected cities include East Coast hubs such as New York City, Philadelphia, Washington, and Baltimore, as well as Midwestern cities including Chicago, Detroit, Indianapolis, St. Louis, and Indianapolis. Southern cities like Memphis, Little Rock, and Dallas will also face intense heat.
The NWS anticipates that these high temperatures will persist into next weekend across the mid-Atlantic, Southeast, and Great Plains.
Temperatures are expected to reach the 90s and low 100s. Due to high humidity, heat indexes could range between 100F and 115F.
“This level of heat is impactful for everyone,” Putnam stated. “It isn’t just a concern for older adults, young children, or those working outdoors; this is heat that can affect anyone, particularly as people spend more time outside during the holiday weekend.”
The heat index accounts for humidity to provide a more accurate sense of how the temperature actually feels, which is critical for assessing the risk of prolonged exposure or strenuous physical activity.
AccuWeather meteorologist Tyler Roys noted that temperatures will sit significantly above seasonal norms. For instance, while Washington D.C. typically sees July highs around 89F and Indianapolis averages 85F, both cities could see temperatures 10 to 11 degrees higher during this period.
Roys described the phenomenon as a “heat dome,” where a high-pressure system of sinking air acts as a barrier, forcing storms to move around it and limiting rainfall across the East.
Furthermore, nighttime temperatures may remain in the 70s or even high 80s, offering little relief from the heat.
Roys warned that for those without air conditioning—particularly in Eastern Seaboard cities like New York, where nighttime lows may not drop below 80F—sleeping will be extremely difficult.
Roys added that this-period is a high-risk time for heat-related illnesses, as the body struggles to cool down and recover.
The National Weather Service advises the public to limit outdoor activities, stay hydrated, and ensure access to air conditioning or designated cooling centers.
Additionally, the NWS warned of extremely dry and windy conditions that could fuel rapid wildfire spread across the Southwest and Great Basin.
In recent conditions near the Utah-Colorado border, three firefighters serving with the US Forest Service and US Wildland Fire Service were killed, and two others were injured, after being overtaken by fast-moving wildfires fueled by extreme heat and wind.
Wildfire-related activity continues to intensify across the Western United States, driven by the-hot, dry conditions in states like Arizona, Colorado, and Utah.
Experts note that these extreme weather patterns and heightened wildfire risks are symptoms of the ongoing global climate crisis, driven primarily by carbon emissions from fossil fuel consumption.
