(CNN)-- The first major heat wave of the summer blanketed the U.S. East Coast on Wednesday with scorching temperatures that swept across the region.
Hot air -- often in excess of 90 degrees -- stretched from Maine to North Carolina, with the highest temperatures hitting parts of Connecticut, Massachusetts, New York, New Jersey, Pennsylvania and Maryland, according to the National Weather Service.
"Very few areas are forecast to be below 90 degrees in the Northeast," said agency spokeswoman Susan Buchanan.
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States across the mid-Atlantic also had heat indices that reached 105 degrees, said the National Weather Service, which issued warnings and advisories across the region.
Heat indices combine temperature and relative humidity to indicate how hot the body feels.
New York City and parts of northeast New Jersey are expecting the heat index to reach even higher. Actual temperatures reached the mid-90s on Wednesday.
"I wouldn't say this is highly abnormal," said meteorologist Rick Watling. "Having heat advisories or even warnings this time of the year is not too unusual."
The National Weather Service advises residents to wear lightweight and loose-fitting clothing, drink plenty of water, take frequent breaks in shaded or air-conditioned environments, stay out of the sun and check on relatives and neighbors.
Young children and the elderly are especially at risk for heat-related injuries, the service said.
Last year, it reported 206 heat-related deaths. In the past decade, heat has been the second-leading cause for weather-related fatalities, the service said.
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Cities across the Northeast designated cooling centers and have issued advisories in an effort to help keep residents safe, according to emergency management officials in several cities.
"For the most part, they're places that are already open and they're designated for when the heat rises," said New York Emergency Management spokeswoman Judith Kane. "The centers are places like senior centers that will be open to the public. It's an effective way to get access to air conditioning if you don't have it."
Residents are advised to call 311 or to go to their city's website online to find cooling centers and to get further information on how to keep cool as the heat rises.