Millions are under extreme heat alerts across the Great Lakes and Northeast starting this weekend as a blistering heat wave sets up in the regions. Highs will be up to 20 degrees above average, and over 100 high temperature records could break by midweek. Some cities included in the extreme heat are New York, Chicago, Boston and Philadelphia. If you are in any of those areas, make sure you have planned out a way to stay cool as the temperatures rise, and be sure to check in on your neighbors and loved ones, especially the elderly.