From the National Weather Service in Pittsburgh:
EXCESSIVE HEAT WATCH IN EFFECT FROM FRIDAY AFTERNOON THROUGH SATURDAY EVENING… THE NATIONAL WEATHER SERVICE IN PITTSBURGH HAS ISSUED AN EXCESSIVE HEAT WATCH, WHICH IS IN EFFECT FROM FRIDAY AFTERNOON THROUGH SATURDAY EVENING.
* HEAT INDEX VALUES…NEAR OR ABOVE 105 DUE TO TEMPERATURES IN THE MID 90S, AND DEWPOINTS IN THE MID 70S.
* TIMING…FRIDAY AFTERNOON INTO EARLY EVENING, AND AGAIN SATURDAY AFTERNOON INTO EARLY EVENING.
* IMPACTS…HEAT STROKE, HEAT EXHAUSTION AND OTHER HEAT RELATED ILLNESSES WILL BE POSSIBLE, ESPECIALLY IF YOU SPEND A SIGNIFICANT AMOUNT OF TIME OUTDOORS, OR ARE INVOLVED IN ANY STRENUOUS OUTDOOR ACTIVITY. PRECAUTIONARY/PREPAREDNESS ACTIONS… AN EXCESSIVE HEAT WATCH MEANS THAT A PROLONGED PERIOD OF HOT TEMPERATURES IS EXPECTED. THE COMBINATION OF HOT TEMPERATURES AND HIGH HUMIDITY WILL COMBINE TO CREATE A DANGEROUS SITUATION IN WHICH HEAT ILLNESSES ARE POSSIBLE. DRINK PLENTY OF FLUIDS, STAY IN AN AIR-CONDITIONED ROOM, STAY OUT OF THE SUN, AND CHECK UP ON RELATIVES AND NEIGHBORS.
Check out THIS LINK FROM THE AMERICAN RED CROSS about staying safe in the heat!