The first heat wave of the summer season has claimed its first victim.
The unidentified woman died in her bedroom. There was no air conditioning and the bedroom windows were shut, but a fan was running, officials said.
Temperatures reached 93 degrees on Monday with the heat index climbing into the mid-90s. The heat index, which is a combination of the actual temperature and relative humidity, determines how hot it actually feels.
The cause of death was ruled heart disease and heat exposure.
City officials are urging residents to open windows during the hottest parts of the day and use fans if they can. Leaving windows shut can essentially turn a home into an oven.
Get more: NBC Philadelphia Weather