What makes this U.S. heat wave so dangerous
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The heat wave sending temperatures soaring well into the 90s°F to around 100°F from the Midwest to the Northeast is a slow-motion disaster that gets progressively more harmful each day.
Why it matters: The heat wave is a public health threat as well as an economic blow. That's because of its large footprint, the fact that it is affecting areas unaccustomed to extreme heat and is an early-season event.
Threat level: Three aspects of this heat wave make it particularly dangerous.
- First is the timing, since such heat is so rare at this time of year.
- Then there's the fact that it is the season's first extreme heat wave. This heightens the risk to those without access to cooling, the very young and elderly, and those with chronic health conditions.
- Lastly, there's the duration. Long-lasting events are more likely to lead to infrastructure malfunctions, from power outages to the melting of airport tarmacs.
Extreme heat also can slow outdoor work and snarl transportation networks, particularly railways and airports.
- And longer heat waves escalate human health risks, studies have shown.
- There's yet another factor to add to the list, according to the National Weather Service: light winds throughout the long-lasting event. This, plus the other characteristics, "will increase the danger of this heat beyond what the exact temperature values would suggest," the agency stated in a post on X.
Zoom in: Studies have shown that economic productivity takes a hit during extreme heat events, and that climate change is likely to worsen these impacts in the future.
- Some research even suggests that outdoor workers' injury rates increase in hotter temperatures.
- Climate change is making heat waves more likely, more intense and longer-lasting, in some cases even yielding extreme events once thought to be "virtually impossible" in a climate without additional greenhouse gases from burning fossil fuels.
- According to Climate Central's Climate Shift Index, at least 25 million people in the eastern U.S. will see daily average temperatures that climate change made at least 4 times as likely between Tuesday and Thursday.
Between the lines: This particular heat wave is likely to slowly build throughout the week in East Coast cities from Washington, D.C. to Boston, while also affecting inland regions from Ohio to southeastern Canada.
- While the midweek period may only be in the mid-90s in D.C. and Philadelphia, the Friday-through Sunday period could see both cities flirt with the century mark each day — a rarity in any summer, let alone during mid-June.
- Many locations will not only set records for daily high temperatures and warm overnight minimum temperatures, but they also may set milestones for long duration heat. In addition, a smattering of monthly records could fall.
- In a sign of how anomalous this event is, the heat dome itself may set records for its intensity, since such weather features cause air pressure surfaces to bubble upwards in altitude.
- The height of a particular pressure surface is likely to come near to or reach record levels later this week across the Mid-Atlantic and Northeast, indicating a stifling air mass below.
By the numbers: According to NOAA's new HeatRisk tool, numerous heavily populated cities are likely to experience Level 4, or "Extreme" heat risk. The tool is a color-numeric-based index providing a forecast risk of heat-related impacts.
- According to NOAA: "This level of rare and/or long-duration extreme heat with little to no overnight relief affects anyone without effective cooling and/or adequate hydration. Impacts likely in most health systems, heat-sensitive industries and infrastructure."
- Locations likely to see Extreme levels of heat risk through June 23 include: Chicago, Detroit, Columbus, Cleveland, Pittsburgh, Albany, Montpelier, Vt., Concord, N.H., Philadelphia, Indianapolis, St. Louis, Grand Rapids, Lansing, New York City, Newark, Cleveland, Washington, D.C.
- Many other cities, with tens of millions more people, will be in the "Major" heat risk category.
- And for millions, this weekend will not mark the end of this hot weather, either. In some places, it could carry over until the end of the month.
The intrigue: The ongoing, high-impact extreme heat event will be felt by at least 230 million people, and yield disruptions in transit, potentially crowd emergency rooms with patients experiencing heat-related illness, and more.
- Yet heat waves cannot currently be classified as federally-declared major disasters under the Stafford Act, in the way that floods, tornadoes or hurricanes can.
- Such a declaration would allow for reimbursement of steps taken to protect vulnerable populations, such as opening and staffing cooling centers, responding to power outages and other potential measures.
- A coalition of groups is petitioning FEMA to change that, and there is legislation pending in Congress that would add heat waves to the list of eligible disasters.
Yes, but: The HeatRisk tool is one way in which the Biden administration has sought to respond to the problem of increasingly frequent, severe and long-lasting heat waves.
