Updated 07/04/12 – 4:14 p.m.

CHICAGO (CBS) — Chicago matched a 101-year-old record on Wednesday, as the official temperature hit 102 degrees in the city.

CBS 2 Meteorologist Steve Baskerville reports it was only the second time the mercury hit triple digits on July 4 in Chicago, since records were first kept in 1871. The last time it was this hot was 1911, when the record of 102 was set.

Any 100 degree day is a big deal in Chicago, which has only seen about 60 days with triple digit temperatures since 1871. The last time was last Thursday, and the mercury could hit triple digits again on Thursday and Friday. That hasn’t happened since 1947.

Due to the extended high temperatures, an excessive heat warning is in effect until 6 p.m. Friday for Cook County — meaning a prolonged period of hot temperatures is expected — and a heat advisory is in effect until 10 p.m. Friday outside of Cook County. Parts of downstate Illinois, southern Wisconsin, northern Indiana and southeast Michigan also are under an excessive heat warning.

Wednesday and Thursday also have been declared Air Pollution Action Days, due to the excessive heat and the debris expected in the air from fireworks for the 4th of July, meaning certain groups might experience difficulty breathing due to high ozone levels. Those at risk include people with lung diseases such as asthma, bronchitis and emphysema; children; the elderly; and those who exercise or work vigorously outdoors.

Anyone who goes outside should take extra precautions to protect themselves from the heat, including covering their heads to provide shade; drinking plenty of fluids; avoiding sugary or caffeinated drinks; and wearing light, loose-fitting clothing.

CBS 2’s Marissa Bailey reports everyone was finding different ways to deal with the sweltering conditions.

Thermometers in the car, and at the bank all read triple digits in Chicago on Wednesday, but you know it’s hot when the dog parks are empty, and even the fish are hiding in the shade.

“I can’t even talk about the heat, I’m roasting,” said Scott Dolan as he and Jon Vondruska cleaned the “Land Lady” before taking a cruise on Lake Michigan on Wednesday.

Vondruska said, after working up a hefty sweat to clean off the boat, they planned to cool off by “staying in the water the whole day.”

Meantime, Charse Nix was the man behind the grill on Wednesday at Union Park. He said, even in this heat, he doesn’t mind barbequing.

“I got a towel to wipe my face off, keep the sweat off my face. It’s in the shade though, so it’s pretty cool over here,” he said.

Keeping cool is the goal, especially for the Wyllie family visiting from Toronto.

“We are scaling back a little bit on how much we do each day, because they need rest and the hotel pool,” she said of her kids.

A slight chance of thunderstorms in the afternoon likely won’t cool things off much if they do occur.

The heat and high humidity can cause a dangerous situation, in which heat illnesses are possible. Anyone who has to be outside is advised to drink plenty of fluids, wear loose-fitting clothing, and stay out of the sun.

Checking up on relatives is also necessary under conditions such as these, the weather service emphasizes.

Wednesday night’s temperature is expected to drop to a low of only about 78 degrees.

The high temperature for Thursday is also expected to reach 102 degrees, and Friday’s high is forecast to be 99 degrees, but could also hit 100. The weekend will bring a bit of a cooling off, so to speak, with a high of 90 on Saturday, and 84 on Sunday. The high on Monday and Tuesday is expected to be 85.