June to end with stretch of 90 F temperatures from New York City to Washington, DC

By Brett Rathbun, AccuWeather meteorologist

The first stretch of pronounced summer heat will continue across the mid-Atlantic states through Friday.

The northern push of the jet stream and area of high pressuresituated across the Tennessee Valley has allowed very warm air to spread eastward from the Plains to the East Coast this week.

This pattern will continue through Friday of this week.

Highs through Friday will generally be in the 80s Fahrenheit across the interior to the 90s F along the Interstate 95 corridor from New York City to Washington, D.C.

Philadelphia, Baltimore and Washington, D.C., are just some of the cities that are on pace for their first official heat wave during the summer season. After topping out at 90 F or above on Wednesday, each of these cities is forecast to reach or exceed 90 F on Thursday and Friday.

A heat wave is defined as three consecutive days of 90 F or higher.

This would be the second heat wave of the year for Baltimore and Washington, D.C., with the first occurring during the spring from May 28-30.

Some other major cities that could take a run at their first 90-degree day of the year include Providence, Boston and New York City.

Dry weather will accompany the heat for many through Friday. The greatest areas for afternoon thunderstorms will be across the Ohio and Tennessee valleys during Thursday and Thursday night and the central and southern Appalachians on Friday. A few late-day thunderstorms can reach the western portions of New York and Pennsylvania on Friday.

This weather will favor those wanting to partake in outdoor activities, such as golfing, fishing and hiking. The dry weather will also benefit outdoor sporting events and concerts.

Humidity levels will not be as oppressive as they can be during the peak of the summer season, but will be noticeable for many. Energy demands for the usage of fans and air conditioners will be on the increase.

The combination of hot and humid conditions will push AccuWeather RealFeel® Temperatures near or above 100 F in parts of the region.

This persistent weather pattern will lead to poor air quality in parts of the area into this weekend.

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"Children, the elderly and those with asthma or other respiratory ailments should limit time outdoors and take frequent breaks from the heat, particularly during the late afternoon and early evening when temperatures are highest," AccuWeather Meteorologist Kyle Elliott said.

Those spending time outdoors for an extended period of time will want to dress in light-colored clothing and remain hydrated. The best time to partake in any strenuous activity is during the morning.

Those hoping to beat the heat by going to the coastal beaches will endure lower temperatures thanks in part to local sea breezes. However, some water temperatures remain chilly, which can increase the risk of cold water shock.

There may be a brief period of relief from the hot and humid conditions this weekend, according to AccuWeather Meteorologist Ryan Adamson.

"A storm system bringing a round of showers and thunderstorms on Saturday will ease the hot and humid conditions across the region on Sunday," Adamson said.

High temperatures on Sunday will average 5 to 10 degrees F lower from their highest marks this week.

"However, the farther south you go, the less noticeable the relief will be," Adamson said.

This generally includes areas south of the Mason-Dixon Line. Baltimore and Washington, D.C., may remain in the 90s F through this weekend and into next week. However, Philadelphia may only peak in the upper 80s F on Sunday when compared to reaching the 90s F during the days prior.

Heading into the first few days of July, more building heat across the central Plains is expected to shift eastward into the mid-Atlantic and Northeast with more 90-degree days to come.

Download the free AccuWeather app to see how high temperatures will get in your community this week. Keep checking back for updates on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.