The National Weather Service early Monday morning issued an excessive heat warning to last through 8 p.m. Wednesday.
A nearly stationary high pressure system to the south will produce hot air and muggy nights for the Philadelphia area. The latest heat wave could last six to seven days, the NWS warned, and is expected to produce triple-digit heat-index values for at least the next few days.
The high temperature for Philadelphia the next three days is forecast to be 96 degrees on Monday, 96 on Tuesday and 97 on Wednesday, with heat-index values of 100 to 103 each day in the afternoon, according to NWS.
While the current excessive heat warning only runs through Wednesday evening, NWS cautions the hottest days could come Thursday and Friday, when heat indices could reach 105 degrees.
The heat wave could break on Sunday, with a high of only about 85 degrees forecast by NWS.
The National Weather Service offers the following advice to keep safe during heat waves: