4 Things To Know About The 1st Major U.S. Summer Heatwave
For meteorologists like me, summer started on June 1. However, the calendar says the summer solstice is today. The atmosphere got the memo as the first major summer of 2025 will descend upon the United States this weekend into next week. Here are four things that you need to know about it.
On this day with the longest duration of daylight hours in the Northern Hemisphere, the Earth is tilted at its maximum angle towards the sun and marks the start of astronomical summer. While the U.S. has already experienced hot temperatures, nature is about to take it up a notch with several days of life-threatening heat across much of the country. The main core of major heat on Friday is expected in the Great Plains and Midwest.
By Sunday, the core shifts slightly eastward and intensifies. The National Weather Service heat risk map indicates extreme conditions affecting places like Omaha, Chicago, and St. Louis. Moderate and major heat risks are expected from Sunday into late next week for almost every location east of the Rockies.
As we move into the work week, the core of extreme heat shifts further eastward. Cities like Atlanta, Washington D.C., Cincinnati, Charlotte, and New York will be sweltering in temperatures within the range of 95 to 100+ degrees F for several days. When the humidity is factored in, the heat indices and wet bulb globe temperatures will be at dangerous levels for activity, exertion, and our infrastructure.
For example, earlier this week reports surfaced about how U.S. heat was affecting the FIFA Club World Cup. Several locations have outdoor venues. Many international players, particularly from Europe, have complained about the level of exertion in heat that they have never experienced. Venue workers and fans have also been affected by the heat. Unfortunately for many of the venues in the eastern half of the U.S., it is about to get worse.
The short answer has been alluded to already. It's the beginning of summer. However, let's dig into the meteorology a bit more. As a meteorologist, my 'weather' senses tingle when I see a large, sustained high pressure system on the map at this time of year. I know that can mean persistent, dangerous heat or drought. Low pressure systems are often the focus of meteorologists and the public because they are often associated with storm systems, rainfall, and hazardous risks. Like the heat risk in general, high pressure systems or anticyclones are often overlooked. High pressure during the summer is typically associated with less cloud cover, sinking air, and hot conditions.
Weather map for the U.S. on June 22, 2025.
NOAA and NWS
The NWS Weather Prediction Center wrote, "A notably strong upper high will be centered over the Ohio and Tennessee Valleys into the Mid-Atlantic next week, continuing a significant and extremely dangerous heat wave across much of the
eastern half of the lower 48." Another key component of this brutal stretch of heat is moisture. The map below shows expected dewpoint temperatures by the middle of next week. The combination of extreme heat and moisture equals dangerous conditions.
Extreme temperatures are the deadliest weather in the U.S. annually. However, people do not react to it in the same way they do tornadoes, hurricanes, or even lightning. Heck, even many media outlets showing kids playing in pools or eating ice cream rather than portraying heat as a serious risk. The extreme daytime temperatures expected with this heatwave are very concerning. It is critical that we all treat extremely hot days differently.
U.S. Weather fatalities in 2024.
NWS
As with hurricanes and tornadoes, there is planning that you can do now (see graphic below) for extreme heat. Elevated nighttime temperatures with high humidity can be even more dangerous, particularly for elderly populations or people with inadequate cooling options. Check on vulnerable people in your personal circles and don't forget pets too. Finally, be sure you can recognize signs of heat stroke, heat exhaustion, Rhabdomyolysis, heat syncope, heat rash, or heat cramps.
Extreme heat planning guidelines.
NOAA
Heat impacts people, animals and plants, but it also affects critical infrastructure. Primary impacts are observed in our transportation networks, energy systems, and water supply infrastructure. However, other impacts include drought implications, wildfire risk, crime or aggression, and increased activity in healthcare facilities such as hospitals or urgent care.
Extreme heat affects our infrastructure.
NOAA and NWS
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