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Dangerous heat wave to broil northeastern US this weekend through July 4th holiday

By Alex Sosnowski, AccuWeather senior meteorologist
June 28, 2018, 7:36:35 AM EDT

A significant heat wave will build and air quality will deteriorate over the northeastern United States this weekend, and it is likely to last into July Fourth in part of the region.

In the northern part of the nation, a heat wave is defined as three days in a row with high temperatures at or above 90 F.

There is the potential for many locations to have highs well into the 90s over a three- to five-day stretch.

Static Heat Wave NE

"While heat waves are common around Independence Day, this pattern could bring the hottest early July weather for such a broad area of the Northeast since 2012," according to AccuWeather Meteorologist Evan Duffey.

Pools, beaches, fans and air conditioners will be abuzz with activity as the major summer holiday approaches. Ice cream trucks and parlors are likely to do a brisk business.

"Energy demands will be high, especially in households around the region with many people off on vacation and out of the office starting this weekend," Duffey said.

Heat Peaks Northeast 6.27 AM

This graphic shows anticipated high temperatures in degrees Fahrenheit. AccuWeather RealFee® Temperatures will be several degrees higher than the actual high temperature.

Businesses that are shut down this weekend into next week may want to help conserve energy and reduce the risk of a brownout, which is a drop in voltage caused by high electricity demand. Thermostats can be set to a higher temperature when employees are not on duty.

Daily record high temperatures in the Northeast are generally in the upper 90s to lower 100s this time of the year, so many records may remain in tact with this heat wave. However, portions of southern Canada may challenge record highs.

AccuWeather RealFeel® Temperatures will climb above 100 for a few hours most days with the worst conditions in the urban areas.

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The RealFeel Temperature factors in many more parameters than the temperature and humidity, with sun intensity being one of these.

The sun is about as strong as it gets this time of the year. The summer solstice, when the sun's rays were most intense, was on June 21.

"The heat will first build over the Midwest, next southern Ontario and the central Appalachians and finally the coastal Northeast," according to AccuWeather Senior Meteorologist Brett Anderson.

Static Heat Arrival 3 pm

Even though it's supposed to be hot in the summer, this can be dangerous

The air may stagnate over much of the region, including the major Interstate 95 cities from Richmond, Virginia, to Washington, D.C., Baltimore, Philadelphia, New York City and Boston.

"A lack of strong surface winds may result in a buildup of pollutants, such as ozone, and cause poor air quality in general," Anderson said.

People with respiratory problems are urged to stay in an air-conditioned environment. Homeowners who do not have air conditioning may want to set up an area in a cool basement to spend time out of the heat.

There will be an elevated risk of heat exhaustion and heatstroke during the upcoming weather pattern.

Urban areas can become unbearable without air conditioning. Once the sun heats the brick, concrete, and pavement, these surfaces will give off the heat through the night. Urban cooling stations will be needed where practically no relief from the heat is likely.

People are urged to drink plenty of liquids and limit their intake of alcohol in weather patterns such as these. Alcohol can accelerate dehydration.

Avoid prolonged strenuous physical activity, especially during the heat of the day from late morning through the afternoon. For those who feel the need to exercise or must do manual labor, the early mornings, evenings and nights are best.

Be sure to check on the elderly and young children on a regular basis.

Motorists are encouraged to reduce their speed on the highway and keep tires properly inflated to lower the risk of a blowout during extreme heat.

Little chance of storms during first part of heat wave

Most locations will be free of rain this weekend.

However, during early next week, the risk of spotty thunderstorms will increase with building humidity.

The first storms are likely to fire over the Great Lakes, then the central Appalachians early next week. Spotty storms may continue over the Appalachians into the middle of the week.

Along the I-95 corridor, spotty thunderstorms are possible on July Fourth.

Best weather to be at the beaches

For those heading to the Atlantic beaches, the entire time from Saturday through Wednesday may be free of rain from Virginia to southern Maine.

"The coolest spots in this pattern are likely to be right on the beach, due to a weak sea breeze, rather than over the mountains," Anderson said.

Ocean water temperatures range from near 60 along the southern Maine coast to within a few degrees of 70 along the New Jersey beaches to near 80 at the Virginia capes.

Remember to always swim with a buddy to increase your chance of prompt medical treatment following cold water shock.

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