 More than 100 million Americans under heat advisories with more record highs expected this week. Heat watches and warnings are posted for much of the U.S. northeast, mid-Atlantic, midwest, and deep south today as temperatures soar once again into the 90s, coupled with high dew points making the air temperature feel hotter than it really is. Those heat index values today could be in the high 90s in places like Boston, but also reach 109 in much of North Carolina.