AccuWeather's Jon Porter warns of a dangerous heat wave that is going to grip the Midwest and Northeast regions of the U.S. this weekend. Temperatures could reach triple digits from D.C. to New York.
00:00Chief Meteorologist John Porter, you know, I think we're all looking forward to summer, but heat can be very dangerous.
00:07So let's talk about the pattern, bringing all of it.
00:09That's a great point. We've had many people commenting about where's the heat and humidity been in the central and eastern part of the United States.
00:16We've had a few warm, very warm to hot days, but nothing sustained.
00:20That is going to be changing in a big way.
00:22And look at the pattern that's going to be setting up a big area of high pressure through the atmosphere here across the central part of the United States.
00:29It's on Friday into Sunday, and then that shifts to the east coast by early next week.
00:34This is our big heat dome, and associated with this is unusually hot temperatures.
00:40And this is going to be really noticeable here because it's not only going to be the heat during the day,
00:46there's going to be little relief at night, which sets us up for a dangerous heat wave setup over the coming days.
00:53Do you mind explaining heat dome? I feel like it's a term that starts to get thrown around this time of year,
00:57maybe for people watching to break it down a little.
00:59Yeah, that's a great point. It's a big area of high pressure in the atmosphere,
01:02and associated with that is unusually warm air, hot air, but also associated with it is sinking motion in the atmosphere,
01:11as opposed to rising motion, which produces clouds and precipitation.
01:15Areas of high pressure in the atmosphere have sinking motion, and that also promotes warmer air as well.
01:22So you've got the warm air associated with this heat dome initially,
01:26and then the components of that sinking air in the atmosphere also helps to amplify the heat as well.
01:31So we've got both of those factors that are going to be working here, and it's going to be incredibly humid as well.
01:37As Melissa was just mentioning, we have had all kinds of rounds of rain here in the central and eastern part of the United States over recent weeks,
01:45and so that's going to add to the low-level humidity.
01:47It's going to feel like a jungle in some places.
01:50Oh, great.
01:50All right, well, with the intensity of the heat, AccuWeather has come up with a product.
01:55It's called the Heat Wave Severity Index.
01:57A lot of information to digest on this graphic.
02:00John, if you'll break it down for us.
02:01That's right, and this is another AccuWeather tool to help you understand best plan
02:06and understand the heat-related risks.
02:08Nobody else has a tool like this.
02:10What we do is we actually score each heat wave, and in order to have a heat wave, you need three or more days, consecutive days,
02:17above a specific temperature that varies by city.
02:20In the cities in the northeast, that's 90 degrees, so you need three or more consecutive days with a high temperature above 90 degrees to have a heat wave.
02:28And notice we have not had any heat waves yet here in 2025, but we're forecasting a severity index of 16 for this heat wave
02:36that's going to be coming up over the coming days, and on our scale, that's right in the middle of the strong heat wave category.
02:43It's not a severe heat wave and not an extreme heat wave, but it's still going to be very dangerous,
02:48and you can see how that compares to the four heat waves that we had in 2024 in Philadelphia and the three in 2023.
02:55All right, John, you and I were looking at the exclusive AccuWeather 10-day forecast in Philadelphia,
03:00and while we could be near records some days, it's not so much about, hey, we've never seen temperatures this hot.
03:05It's the duration of the heat and then also what's happening at night.
03:09Exactly. Look at the duration.
03:11We're talking all the way from Thursday on the AccuWeather exclusive 10-day forecast.
03:15Of course, you get this anywhere around the world in the free AccuWeather app.
03:19Look at it. It goes all the way through next Friday and Saturday.
03:22Temperature's still in the 90s.
03:23The peak of the heat early next week, Monday to Wednesday, where temperatures can be near 100,
03:29and then those overnight low temperatures, they fall to only 75 to 80.
03:33That's a problem as well.
03:35All right, let's talk about the dangers of heat here.
03:38We spoke about the overnight temperatures and folks not being able to cool off
03:42and kind of just summarize why the heat can be so dangerous and unfortunately deadly.
03:46A couple of the things that we're very concerned about with this one is that there's an amplified risk
03:50for heat impacts here because it's the first heat wave of the year.
03:54Our bodies are not yet acclimated to it.
03:56There will be little to no heat relief at night, especially in the city centers where many people live.
04:02And, of course, people who are working outside for the first time can be at an elevated risk for heat illness and heat stroke.
04:10This is something I learned last year when I was talking with the Occupational Safety and Health Administration, OSHA,
04:16who, of course, regulates workplace safety.
04:19And they commented that many people who are working outside, for example, for the first time in a new job
04:24or college students or high school students that are working during the summer outside,
04:29maybe not as used to dealing with the extreme heat.
04:31So if you fit into that category or you know somebody who does, let them know to be extra careful,
04:36take extra water breaks, be very careful with this first heat wave of the year.
04:41And, of course, we also want to point out that the heat health impacts accumulate through the heat wave.
04:46So the last day of the heat wave or even the day after the heat wave breaks
04:51can be the most dangerous in terms of the risk for heat illness.
04:55Accurator Chief Meteorologist John Porter, thank you so much for breaking down the heat for us.
04:59And we hope that everybody stays safe and stays cool as we head into the weekend and next week.
