A heat advisory is in place across the Northeast, from Maryland to Maine, where residents are bracing for temperatures 5 to 15 degrees above average.

       The heat index -- what the temperature feels like with humidity -- could reach 103 degrees in Philadelphia on Wednesday and Thursday.

       New York City and Boston could feel like 100 degrees with humidity on Wednesday and Thursday.

       Further north, the heat index may climb into the upper 90s in Burlington, Vermont, and Syracuse, New York, on Wednesday.

       The dangerous heat is also invading the South and West.

       The heat index could hit a scorching 105 to 109 degrees on Wednesday in New Orleans; Memphis, Tennessee; and Little Rock, Arkansas.

       In the West, a heat advisory is in place from Northern California to northern Washington with temperatures 10 to 15 degrees above average. Portland, Oregon, could near 100 degrees on Wednesday and Seattle could reach the 90s.

       Click here for what you need to know to stay safe in the heat.