A haunting reminder from the National Weather Service as dangerous heat envelops the east and west coasts by the start of the weekend, putting almost half the country on heat alarm and potentially breaking daily record highs, breaking record highs on both Thursday and Friday while even more Places have a better chance of observing record daily temperatures from warm lows, “said the Weather Prediction Center. Nearly 58 million people are under excessive heat warning, with major cities like New York, Philadelphia, St. Louis, Kansas City, Seattle and Portland included in this highest level alert.
“Today there are numerous heat warnings and some warnings of excessive heat from the central plains to the northeast. The heat indices in these areas will be between 100 and 110 degrees, with some locations as high as 115 degrees,” the WPC said.
The Pacific Northwest faces another round of dry heat
The heat has started on the west coast and is again concentrating on the Pacific Northwest. Temperatures in the area are expected to rise 15 to 25 degrees above average, with hot and dry heat lingering until the beginning of the weekend.
“Thursday’s temperatures will even challenge some record highs in the Northeast and the Pacific Northwest,” the WPC said.
Seattle will be in the mid to mid 90s on Thursday and Friday, and Portland could even hit 100 degrees by the end of the week. This creates particularly dangerous conditions in a region where many do not have air conditioning. It will be the second major heat wave in the Pacific Northwest this summer. In June, all-time record temperatures fell by the wayside as cities like Seattle rose to 108 degrees while Portland baked at an oppressive and unprecedented 116 degrees. During that period, hundreds more emergency room visits for heat-related symptoms and deaths than usual were reported.
Many may be on their way to the water to recover from the heat, but doing so may pose a new threat.
“Warm air doesn’t always mean warm water in lakes, streams, or oceans. Fifty-five degrees water may not sound like very cold, but it can be deadly. Diving into cold water of any temperature becomes dangerous if you’re not prepared for the sudden exposure can damage your body and your brain, “warns the NWS.
Body heat is lost 25 times faster in cold water and can quickly lead to hypothermia. In the coastal regions of the Pacific Northwest, where hot temperatures are rare, many people flock to the coast.
“Beach attendance rates were high during the June heat wave, resulting in increased rescue rates and deaths,” said the National Weather Service in Portland, Oregon.
Higher air temperatures increase the likelihood of cold shock when entering the water, which can lead to muscle stiffening and drowning.
Seattle’s record for most consecutive days of 95 degrees or higher is four, and if the forecast holds for that week it will hit five.
Hot temperatures in the northeast
On the other coast, heat warnings will extend across northeast North Carolina to Maine by the end of the week.
Highs in the 90s with relative humidity values lead to three-digit heat indices and bring a sweaty, suffocating heat that could break daily records.
Excess heat warnings include major cities of Philadelphia, New York, and Boston through Friday. Actual New York temperatures will be in the mid-90s and won’t drop below 90 until Saturday to hit a high. Washington, DC, could hit 100 degrees on Thursday and see high temperatures not drop below 90 until Sunday.
“A stretch of several days of oppressive to dangerous heat and humidity continues today, which lasts at least until Friday. Today is going to be the most dangerous day in terms of heat and humidity, with heat indices of up to 109 degrees, “NWS Boston said Thursday.
The humidity in the region causes the relative humidity values to rise and the hot weather feels even hotter.
“The main concern tonight is the lack of relief from the heat. Parts of Philadelphia must not fall below 80 degrees,” NWS Philadelphia said Thursday.
Persistent heat overnight can be dangerous and fatal and increase the likelihood of heat-related illnesses.
“This is a problem because those temperatures don’t allow the body to successfully cool off at night,” said CNN meteorologist Allison Chinchar. “The temperature must drop to at least 80 degrees for recovery to begin. In fact, a person can lose up to 2 liters of fluid through sweating overnight if the temperature doesn’t drop below 85 degrees.”
The coastal heat waves come after a summer of record-breaking heat. Heat waves are nothing out of the ordinary, but the scale of recent events has warned climate scientists about what’s to come.
Heat waves are getting hotter because of the climate crisis. With global warming of 2 degrees Celsius, the hottest temperatures would reach nearly 3 degrees Celsius (5 degrees Fahrenheit) higher than previous heat waves.
Burning in the South and Midwest
The Mississippi River Valley will also be exposed to temperatures in the upper 90s for the next few days, with the heat indexes feeling at 110 in some places.
The heat index takes the humidity into account with the temperature, which creates a “tangible” temperature. The human body produces sweat when it warms up to cool itself down, the moisture evaporates and cools the skin. But if the conditions are too humid, the sweat won’t be able to evaporate and it will feel hotter.
St. Louis and Kansas City are both included in excessive heat warnings on Thursday as heat index readings hit the triple digits. There are heat warnings in nearby regions of the Midwest where the urban heat island effect is less intrusive.
Neighborhoods with few trees, few grass areas and a lot of concrete can be up to 15 to 20 degrees hotter than the surrounding area.
Kansas City will experience “dangerously hot conditions with heat index values up to 110 degrees” according to the National Weather Service. The lows are forecast to persist overnight into the low 80s, which will provide little relief from the relentless heat.