The heat index in the Baltimore area is expected to reach up to 109 degrees on Friday during a dangerous weekend heat wave. 

Baltimore is under a Code Red Heat Alert Friday, July 25, through Tuesday, July 29. 

The city has opened its cooling centers to the public. You can call 311 or to find a cooling center near you. 

The extreme temperatures prompted the city Department of Public Works (DPW) to activate its Heat Illness Prevention Plan to keep crews safe. DPW said trash and recycling collections ended early on Friday due to the dangerous heat. All DPW Recycling Centers closed at 5 p.m. to protect crews. 

Red Cross warns of dangerous heat

The American Red Cross is urging Marylanders to protect themselves from extreme temperatures. 

"Extreme heat kills more people in the United States than any other natural disaster," said Scott Marder, a spokesperson with the American Red Cross Central Maryland Chapter. 

The Red Cross encourages people to: 

• Stay hydrated by drinking a cup of water every 20 minutes, even if you don't feel thirsty. Avoid surgery, caffeinated, and alcoholic drinks. 
• Stay cool by spending time in air-conditioned places. If your home is too hot, go to a mall, library or cooling center. 
• Stay connected by checking in on others and asking for help if you need it. Don't forget to make sure pets have access to fresh water and shade. 

Most importantly, pay close attention to signs of heat exhaustion, like vomiting, nausea and weakness, Marder advised. 

Also, know the signs of heat stroke, like dizziness, confusion and high body temperature, Marder said. 

Despite heat, visitors flock to Baltimore's Inner Harbor 

The extreme heat did not stop people from visiting Baltimore's Inner Harbor on Friday. 

"It feels awesome," said Chris Layton, who traveled from Arkansas to Baltimore with his family. "It feels like home."

"Really hot, like sweating," said Astrid Villegas, another visitor.

Whether it's a walk, bike ride or boat ride, several people took advantage of the sunny day.

"Do a little fishing," said Baltimore resident Cedric Booze. "I want to come out here, maybe grab some catfish…salmon."

"The Fantastic Four just came out and I don't want any spoilers," Villegas said. "I'm on my way to that."

Visitors are mindful of the dangerous impact and are all taking the same action.

"We just drink lots of water," Layton said.