Chicago Is About to Sizzle Under Hottest Days of the Summer

(Bloomberg) -- Chicago and the Midwest will swelter under the warmest days of summer as forecasters warn people to limit their outdoor activities. 

Temperatures in the Windy City are forecast to reach 96F (36C) on Monday and 98F on Tuesday, but with humidity it will feel like triple-digit heat, the National Weather Service said. The searing weather will be short lived, with the highs dropping back into the 80s by Wednesday. Electricity prices rose to six-week highs in the Midwest for Monday evening as people ramp up air conditioners. 

In addition to the heat, there is an enhanced risk of severe thunderstorms, which can bring hail and tornadoes, across parts of South Dakota, Minnesota, Wisconsin and Iowa, affecting about 5.7 million people, the US Storm Prediction Center said.

People won’t be as acclimated to the heat and humidity as they would be in a normal August because there has been a lack of such events in recent weeks, the weather service said. High temperatures will pressure electric grids and bring health risks. In July 1995, more than 700 people died during a five-day heat wave across the Chicago region, according to weather service records.

Electricity prices in parts of the Midwest rose the highest levels since mid-July in the day-ahead markets, according to data from the grid operators and Arcus Power’s Nrgstream market data service. 

Hourly prices for delivery Monday evening in Exelon Corp.’s ComEd utility, which serves Chicago, topped $120 a megawatt-hour while areas just southwest of the city in Lemont and Lockport, Illinois, soared to more than $1,000 because of transmission bottlenecks, data from PJM Interconnection LLC show. The elevated prices in ComEd were due to congestion on the transmission system, but they may or may not materialize in real time, PJM spokesperson Daniel Lockwood said in an email.

On the adjacent central US grid, the Midcontinent Independent System Operator warned of the potential for tight supplies from the Midwest to the Gulf Coast on Monday as heat drives up electricity usage. Prices at the Indiana hub climbed as high as $169 a megawatt-hour for this evening, the most since July 15, while the Louisiana hub rose to about $81, the most since at least June, according to Nrgstream. 

“The MISO grid is stable but the extreme heat is driving demand to the highest levels of the summer season,” Brandon Morris, a spokesperson for the grid operator, said in an email.

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(Updates with power prices throughout)

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