Heat Dome Scorches Northeast US Cities With 100-Degree Heat

An intense and nearly historic weather pattern is engulfing much of the eastern United States under a dangerous heat dome this week, with triple-digit temperatures in regions that haven’t experienced such heat in over a decade. This heat wave is particularly threatening because it is affecting major cities like Boston, New York, and Philadelphia early in the summer, when residents have not yet acclimated to the extreme conditions. The high-pressure system trapping hot air from the Southwest has already caused discomfort in the Midwest and is now settling over the Northeast.

A key measurement of the strength of the high pressure broke a record on Monday and was the third-highest reading for any date, making for a “near historic” heat wave, according to private meteorologist Ryan Maue, a former chief scientist. The peak of the heat is expected to hit Northeastern cities on Tuesday, with forecasters warning of dangerous conditions. Maue described the situation as “like an air fryer, it’s going to be hot,” emphasizing the three-day stretch of oppressive heat that will test the resilience of city dwellers, especially those most vulnerable to such conditions.

A heat dome occurs when a large area of high pressure in the upper atmosphere acts as a reservoir, trapping heat and humidity. A heat wave is defined by the persistence of heat, usually three days or more, with unusually hot temperatures. Nearly three-quarters of the country’s population—245 million people—will experience temperatures of 90 degrees Fahrenheit (about 32 Celsius) or higher on Monday, with 33 million people, almost 10% of the country, facing blistering 100-degree heat (about 38 Celsius) on Tuesday. The highest level of heat risk is expected in regions stretching from Chicago to Pittsburgh and from North Carolina to New York.

These extreme temperatures, exacerbated by humidity, are unusual for places like New York, which hasn’t seen 100 degrees since 2011, and Philadelphia, which hasn’t reached that mark since 2012. In downtown Baltimore, temperatures climbed into the high 90s by early Monday afternoon, leading dozens of people to seek refuge at cooling centers. The heat forced the cancellation of events in west Baltimore, with local residents expressing concern for the safety of children and others vulnerable to heat stroke.

Meteorologist David Roth noted that it takes time to acclimate to summer heat, and this sudden heat dome could be a shock for many. The heat is part of Earth’s long-term warming trend, with summers in the United States being 2.4 degrees (1.3 degrees Celsius) hotter than 50 years ago. Human-caused climate change has made this heat wave three times more likely than it would have been without the burning of coal, oil, and gas. A key question is how much humidity will add to the discomfort and danger of the heat. Maue is forecasting dry air, which may be a degree or two hotter but more comfortable. Other meteorologists expect worse conditions, with sticky, humid air making the heat even more dangerous.

University of Oklahoma meteorology professor Jason Furtado warned that the high-pressure system will allow for significant evaporation from wet grounds, increasing heat indices. Chief meteorologist Bernadette Woods Placky expects dew points in the 70s, describing the conditions as tropical and oppressive. If this heat were later in the summer, it might not be as dangerous because the human body can adjust to seasonably warmer temperatures. However, this heat wave is coming within days of the solstice, making it a shock to the system for many residents.