An late-summer heat wave is set to continue through the middle of the week, according to the National Weather Service. Heat index values will exceed 100 degrees an approach 110 in many locations during this timeframe. Extended outdoor activities are not recommended. Although the hottest temperatures will be during the day, overnight lows will only reach the mid 70s, leaving little reprieve from the heat. Relief will begin slowly on Wednesday before a return to seasonal, mild conditions by the weekend.