Boston braces for triple-digit heat index

State of play: Temperatures are expected to reach the mid 90s Thursday and Friday. The heat and high humidity could cause heat-related illnesses, per the National Weather Service.

Zoom out: Late July is typically one of the hottest periods of the year, but Boston summers have become hotter over the past 50 years.

• The heat wave comes as multiple regions worldwide experience extreme heat events tied to climate change.

Flashback: During last year’s heat wave, Boston EMS saw a 15-20% increase in daily 911 calls, according to the mayor’s office.

Details: 15 Boston Centers for Youth & Families community centers will serve as cooling centers 9am-5pm Thursday and Friday.