US Weather: Heat dome pushes temperatures above 100°F in Chicago, New York, DC and Philadelphia by July 4 | Today’s news
A massive heat dome is expected to spread across much of the central and eastern United States this week, bringing days of dangerous heat, extreme humidity and unusually warm nights to more than two dozen states over the Independence Day weekend.
Forecasters are warning that temperatures will reach 90 degrees Fahrenheit in many cities, with some locations exceeding 38 degrees Celsius. Combined with high humidity, it will feel even hotter, increasing the risk of heat illness.
What is a heat dome?
A heat dome is a weather pattern in which a strong area of high pressure traps hot air over the area for days or even weeks.
Descending air beneath a high-pressure system suppresses cloud formation and rainfall, allowing the sun to continually warm the earth. Trapped heat builds up every day, so temperatures gradually rise.
Where will the heat hit the hardest?
The most intense heat is expected in the Mississippi Valley, Ohio Valley and parts of the eastern United States.
According to AccuWeather, cities expected to experience prolonged extreme heat include:
Chicago: Four to five consecutive days at or above 90F
St. Louis: At least eight days in a row in the 90s with temperatures nearing 100 F
Philadelphia: Up to three days around 100F
Washington, DC: Up to four days at or above 100 F
New York City: Temperatures could reach 100 F for a few days
Newark, New Jersey: More likely to top 100F for at least two days
Many of these temperatures are well above normal in late June and early July.
Why humidity makes heat more dangerous
Meteorologists say the combination of high temperatures and tropical humidity will greatly increase health risks.
“The setup will bring widespread highs in the 90s F with high humidity across a wide area of the Mississippi and Ohio valleys this week,” AccuWeather Meteorologist Alex Duffus said.
“People who don’t mind the heat will be very uncomfortable if they don’t have air conditioning.”
Duffus added that dew point temperatures will remain in the 70s in many areas.
A dew point above 70 F means very humid conditions, making it much harder for sweat to evaporate and cool the body. This increases the likelihood of heat exhaustion and heat stroke, especially during prolonged outdoor activity.
Warm nights offer little relief
Forecasters say one of the most dangerous aspects of this heat wave will be unusually warm nights.
“While there will be a few places that hit record highs during the day, there could be many more where the record heat occurs at night,” said AccuWeather meteorologist Brandon Buckingham.
In several major cities, nighttime temperatures can remain above 80 F, preventing homes and buildings from cooling and increasing health risks, especially for vulnerable populations.
Urban areas are particularly susceptible because concrete, asphalt and buildings absorb heat during the day and slowly release it overnight – a phenomenon known as the urban heat island effect.
It will feel much warmer than the thermometer indicates
Even where air temperatures stay in the low 90s, RealFeel temperatures can exceed 100 F and in some places rise above 110 F due to humidity, sunshine and light winds.
Smoke from wildfires can worsen conditions
Smoke drifting eastward from wildfires in the western United States could slightly reduce sunshine and reduce daytime temperatures by several degrees in some areas.
But forecasters warn that the smoke could also combine with stagnant moist air to create poor air quality, posing an additional risk to people with asthma and other respiratory problems.
Read also | Climate change and you: Intense heat threatens players at World Cup
When will the relief come?
Forecasters expect a shift in the jet stream over the Independence Day weekend, pushing the heat dome back toward the plains.
This change should allow cooler air and more frequent thunderstorms to spread to parts of the east.
Cities like Boston may start to cool off before the 4th of July, while Washington, DC, may not see significant relief until late on Independence Day or the following day.
Safety advice
Health professionals recommend:
Stay hydrated by drinking plenty of water.
Limit strenuous outdoor activities during the hottest hours.
Spending time in air-conditioned buildings or cooling centers.
Take frequent breaks when working outside.
Check on elderly relatives, young children and people with chronic illnesses.
Keep pets indoors during the hottest part of the day, provide them with fresh water and avoid walking with them on hot pavement.
Meteorologists warn that prolonged exposure to extreme heat and humidity can quickly become life-threatening, especially during multi-day heatwaves when overnight temperatures remain unusually high.
Read also | European shoppers strip shelves without portable air conditioners amid heat wave
