Chicago Forecast

Chicago heat wave updates: Heat index values soared above 120 degrees in some areas, NWS says

An excessive heat warning for all of Northeastern Illinois will go into effect from 11 a.m. Wednesday until 8 p.m. Thursday

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Get ready for the hottest temperatures of the year, Chicago.

Beginning at 11 a.m. Wednesday, an excessive heat warning will go into effect for all of northeastern Illinois and much of Northwest Indiana, an alert from the National Weather Service said.

According to the NWS, the excessive heat warning will continue until 8 p.m. Thursday.

Temperatures Wednesday are expected to hit 98 degrees, according to the NBC 5 Storm Team, which would break a record of 97 degrees set in 1947. And according to NBC 5 Meteorologist Alicia Roman, the mercury Wednesday could go even higher.

MORE: 6 cold-weather activities to look ahead to on 1 of Chicago's hottest days of the year

"Our air temperature may hit 100 degrees in some places," Roman said. "I wouldn't be surprised to see that."

According to the NWS, heat index values of 105-115 degrees can be expected Wednesday, resulting in "dangerously hot conditions."

"Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun and check up on relatives and neighbors," an alert from the NWS said. "Young children and pets should never be left unattended in vehicles under any circumstances."

As the heat and humidity builds, we're keeping track of updates here.

Thousands without power in Wisconsin, Illinois amid staggering heat wave

Thousands of customers are without power in Wisconsin and Illinois amid a heat wave that has driven heat indices north of 115 degrees on Wednesday.

According to WE Energy in Wisconsin, there are nearly 4,000 customers without power in areas around Kenosha County, while hundreds are without power in Illinois, according to ComEd.

As of 3:15 p.m., there were 14 outages impacting 3,782 customers around Kenosha, according to WE Energies.

According to ComEd, approximately 2,770 customers in Illinois were without power as of 8:25 p.m., primarily in Cook County.

Hottest temps in history?

The heat wave is bringing staggering temperatures to the Chicago area, but will it challenge for the throne as the hottest day in recorded history?

It doesn’t appear so, according to the NBC 5 Storm Team. Highs are expected to reach into the upper-90s on both Wednesday and Thursday, and heat indices have already jumped above 115 degrees in many locations on Wednesday.

According to the National Weather Service, the warmest official high temperature recorded in the city came on July 24, 1934, when the high was clocked at 105 degrees.

Wednesday's high temperature could potentially break the record for Aug. 23, with the mercury hitting 97 degrees in 1947, according to the National Weather Service.

Read more here.

Metra implements speed restrictions

Riding the Metra this week? Your train may run a bit slower.

Officials with Metra say that the agency is ordering a reduction in speed on all trains because of the extreme heat currently gripping the Chicago area.

Those restrictions, which will be in effect Wednesday afternoon, will likely lead to delays throughout the Metra system, with officials asking riders to allow extra time to complete their journeys.

According to Metra officials, when temperatures exceed 95 degrees, trains must reduce speeds by at least 10 mph to compensate for heat-related stress on the tracks.

Here's the full story.

Heat Index values could reach even higher than predicted

An alert sent shortly after 11 a.m. from the National Weather Service indicated that heat index levels in some areas could rise to levels even higher than 115 degrees.

According to the NWS, in McHenry, Lake, DeKalb, Kane, DuPage, LaSalle, Kendall, Grundy, Kankakee and Will counties, heat index values of between 112 and 118 degrees are expected.

In Cook County, heat index values of between 110 to 115 are expected, the NWS said.

Excessive heat warning now in effect

All of northeastern Illinois is now under an excessive heat warning, the National Weather Service says. According to the NWS, the warning will continue through 8 p.m. Thursday.

In a tweet, the NWS noted that at 10 a.m. Chicago had already hit a dew point temperature of 79 degrees with a heat index of 103 degrees. According to officials, there have only been six other times this has occurred.

By 12:35 p.m., the heat index at O'Hare had already reached 116, the NWS said.

Chicago-area schools cancel athletic activities, plan for early dismissal

Schools around the Chicago area are tweaking their schedules and making alterations to their activities in coming days because of the heat.

Here are the latest changes we know of:

  • Chicago Public Schools will cancel all outdoor athletic games on Wednesday and Thursday, and will move all practices indoors on those dates
  • Plainfield School District 202 says it will keep students inside for recess, physical education, athletics and other activities both Wednesday and Thursday
  • Mount Carmel High School will shift to half-day schedules beginning Wednesday, with school dismissing at 12:10 p.m. for the remainder of the week. Sports practices will be moved to morning hours.
  • Lyons Township High School District #204 will implement early dismissal scheduling, with education taking place from 7:45 a.m. to 11:30 a.m.
  • Valley View’s Lukancic Middle School has canceled baseball and softball games, as well as cross-country meets, from Tuesday to Thursday because of the heat.
  • Oak Park River Forest High School will hold PE classes indoors Wednesday and Thursday. Classes held in rooms without air conditioning will be temporarily moved. All athletic practices will be moved to hours before school begins.
  • Downers Grove School District 58 will delay the start of school Wednesday to Friday "due to the forecast of extreme heat conditions."
  • Crystal Lake District 47 - Canterbury and West Elementary will be closed until Friday

According to CPS officials, all classrooms have air conditioning, and crews will work to fix any cooling problems that arise this week.

Symptoms of heat stroke vs. heat exhaustion

Dangerously-hot temperatures are about to arrive in the Chicago area, and experts are urging the public to acquaint themselves with the symptoms of heat-related illness.

"The biggest problem is, once again, the way that our body usually dissipates heat to keep our temperature where it should be is through sweating and then evaporation of that sweat off the bod," Lewis said, adding that with high temperatures and high humidity, "what happens is, it's very hard for our body to evaporate that heat or that perspiration."

"So we really can't cool ourselves. And that's where we get into trouble during these weather conditions," he said.

Symptoms of heat stroke can include confusion, loss of consciousness, hot, dry skin, seizures, or high body temperature. Heat exhaustion symptoms can include muscle cramps, headaches, dizziness and more.

Additional cooling centers in Chicago, Cook county

The city of Chicago has announced it will open additional cooling centers, and will extend cooling center hours, amid dangerously-high heat indices in the area.

A full list of the available information can be found here.

MORE: Chicago Fire Department to escalate responses, activate ambulances ahead of hot weather

Cooling centers are also available in numerous suburban communities, including across Cook County at courthouses Skokie, Maywood, Markham, Rolling Meadows Leighton, Bridgeview and the Daley Center Courthouse.

Visit your county's website to see if there is a cooling center near you.

White Sox 1:10 p.m. game still on

Fans heading to Wednesday’s game between the Chicago White Sox and Seattle Mariners will need to take precautions against overheating, as air temperatures could approach 100 degrees at Guaranteed Rate Field.

First pitch between the clubs is set for 1:10 p.m. Wednesday, and according to NBC 5 Chief Meteorologist Brant Miller, the temperature at that hour in Chicago could potentially reach 97 degrees.

That isn’t where the issues stop, either. According to forecast models, the heat index could potentially soar as high as 115 degrees during the game.

As of 6:30 a.m., the White Sox game was still scheduled to go on.

The best advice for staying safe during Chicago's heat wave

While advice from experts during periods of extreme heat may seem obvious, such heat "often results in the highest annual number of deaths among all weather-related disasters," a spokesperson for Cook County Health said.

So what exactly should residents keep in mind over the next few days as the mercury continues to rise? As NBC Chicago combed through dozens of lists and bits of advice from the Red Cross, the National Weather Service, the city of Chicago and more, these five tips were among the most cited.

What to do if you have car trouble in the heat

Round-the-clock “hot weather patrols” will be launched by the Illinois Tollway this week.

According to officials, those patrols will search for drivers stranded in disabled vehicles, and will respond to *999 motorist assistance calls.

Tollway officials urge motorists to save *999 in their phones in the event of an emergency, and to remain in their vehicles should they need assistance.

Emergency kits with water and jumper cables are also encouraged.

What is the “heat index?”

To put things as simply as possible, a “heat index” is a reading that indicates how the air temperature feels, rather than the official temperature reading.

There are a few limitations to heat indices, including its measurement of shaded, lightly-windy areas instead of sunny areas.

Here's a full explanation.

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