mid-atlantic and even the upper midwest. >> cold water! get your cold water! >> reporter: up and down the east coast, the heat index is pushing 100. >> extended periods of heat can kill individuals. >> reporter: in baltimore, a code red heat alert from the health department. >> we're going to have a series of four really hot days, and so the effects of heat and the stress on the body are going to be cumulative. >> reporter: tourists in times square were feeling it too, where the temperatures cracked triple digits. >> here it's really hot and humid. >> reporter: making it a terrible time for a massive water main repair in maryland's prince george's county, just outside of washington, d.c. >> conserve as much as possible because come tomorrow morning when everybody wakes up and takes a shower, we're going to run out of water pretty fast. >> reporter: officials estimate the outage will impact between