Chicago police then stepped in and ordered everyone to leave, and North Avenue Beach was closed about an hour early.
The thermometer reached the high eighties in Chicago and that sent crowds of people hungry for heat and sunshine outdoors this Memorial Day. It was shortly after 6 p.m. when the Chicago Police Department decided that for "public safety reasons" North Avenue Beach had to be closed.
Beachgoers say everything happened very quickly, leaving most confused as to what exactly was going on.
"We were playing volleyball and we saw police cars started to come in and tell everyone to get out," said beachgoer Sergio Cervantes.
"We just heard a ruckus. It was like a riot. And the police came and shut it down, closed the beach early. It's upsetting," said Micaiah Wilcoxson.
The police department says it all started when ambulances were called to respond to several cases of heat exhaustion. The Chicago Fire Department, unable to gain access because of the huge crowds, called for help. Once inside, emergency responders found an 18-year-old unresponsive, as well as three others, all under the age of 21, in need of hospitalization. Meanwhile, firefighters turned on their misting hoses to help cool people down.
Elsewhere, other incidents were reported though none as major. The Chicago Fire Department's Marine Unit responded to Lake Michigan and Fullerton, where a boat with two people on board was taking in water. Also, they had to rescue a kayaker near Diversey Harbor who had apparently fallen overboard. In Naperville, three water-related incidents took place, including the near drowning of a 4-year-old child. He is now hospitalized.
Hot weather arrives for Memorial Day
As Chicago heated up Monday morning, sun worshipers trickled out to beaches to claim their spots on the sand. By late morning, the beach was packed.
"I've been waiting for this day since October," Monica Aguilera said.
"I need the sun. Yesterday, it was dark at 10 o'clock in the morning," said Kyra Evans.
By early afternoon, Alex Figley and her friends had their fill of the beach after a couple of hours and packed up to go home. They arrived when it was still possible to get a good spot on the sand, unlike Lucas Lambert who was not sure where he will be able to roll out his beach towel.
"Probably pretty hard. It's crowded," Lambert said as he surveyed the crowded beach.
"It's a totally different vibe from the winter. It is a good time to be outside and enjoy the day off work," said Figley.
Mounted officers kept a close eye on the crowd. They kept their horses cool by taking them for an occasional dip in the lake.
"No problems as of yet," Officer Paul Casasanto told ABC7 from his horse.
While many residents soaked up the sun, some enjoyed a game of volleyball. "First well-predicted day of sunshine in four months," said volleyball player Brian DeSantis.
Away from the beach, some people took advantage of the perfect morning eating breakfast on the patio at Tempo Cafe. Because of the change in weather, a group of tourists from Miami said they might actually visit Chicago again.
"The last two days, it's been raining," said visitor Ryan Montgomery. "Feels good to finally be out for some warm weather."
Others were ready to sweat as they ran -- or skip the workout and go straight for the grill. In Washington Park, Glen Scott and his wife came out early to find a place to grill in the shade. When asked what he was grilling, Scott said: "Today I am cooking ribs. I'm also cooking something new that I never cooked before on the grill, and that is turkey chops. Turkey chops!"
The summer weather is dramatically different from what area residents and visitors coped with over the weekend. Thunderstorms Sunday drenched many holiday barbecues and picnics and dumped plenty of rain, flooding parks and streets across the city and the suburbs.
Earlier Sunday, cyclists participating Bike The Drive had to deal with less than summer-like weather. The thick fog hid views of Lake Michigan and Chicago's skyline along Lake Shore Drive.
During the Memorial Day Parade and commemorations in the Loop Saturday, spectators wore pullovers because of the cool weather and had umbrellas ready. Fortunately, the rain held off until after the downtown events ended. ABC7's broadcast of the parade is available on-demand.
It almost looked like the weekend would be a washout and far from the unofficial start of summer, but the last round storms brought more pleasant conditions just in time for Memorial Day, making it a perfect day to cook out or soak up some sun rays. After six or seven months of winter-like, chilly weather, Chicago-area residents deserve it.
