Millions of people across the northeastern United States suffered Friday as temperatures soared above 40 degrees Celsius and hit all-time record highs in many areas.

Extremely high humidity made it feel like more than 45 Celsius in New York and other cities.

Officials say this week's heatwave has killed several people. Dangerous heat and air quality alerts were issued for much of the northeastern U.S. Officials warned people to avoid working outside and seek cooling shelters if needed.

The sweltering heat stretched power supplies across several states, as people blasted air conditioners in an effort to stay cool. New York's power provider reduced voltage in several neighborhoods in an effort to prevent outright outages.

Above average temperatures and poor air quality are expected across the northeastern U.S. Saturday.