UPDATED 07/22/11 8:08 a.m.

CHICAGO (CBS) — The heat may feel a little less oppressive Friday than in it has for much of this week, but temperatures will still be sticky and uncomfortable as they top 90 degrees.

CBS 2 Meteorologist Megan Glaros says the most severe and dangerous heat will be locked mostly to the south.

An excessive heat warning remains in effect until 10 p.m. Friday for Will and Kankakee counties and everything to the south all the way through downstate Illinois, as well as the entire state of Indiana. The extreme heat will be locked in that area.

But a heat advisory remains in effect for the Chicago area, as well as suburban Cook and DuPage counties, also until 10 p.m. Friday.

The National Weather Service says the immediate Chicago area might see some relief Friday from a lake breeze boundary that will push inland, but the landlocked counties to the south will have no such relief.

When the excessive heat warning ends Friday night, a less-dire excessive heat watch begins and continues through Sunday night.

By noontime, the temperature is expected to climb to 90 degrees, and the high is expected in the mid- to upper 90s in the far southern part of the area, but only in the low 90s farther north.

The forecast high for Friday is 92 degrees. Showers and storms are also possible Friday night, as a cold front comes through.

Highs remain in the 90s through the weekend, at 91 on Saturday and 90 on Sunday.

As CBS 2’s Susanna Song reports, 22 people have now been killed nationwide by the brutal heat wave, and now the Cook County Medical Examiner’s office will determine if heat played a factor in several recent deaths in Chicago.

So far, the heat is suspected in at least six deaths — five in Chicago and one in Calumet City. One of the victims was only 18 years old.

Officials say it’s a reminder that neighbors can’t let their guard down, and it’s important to check on the elderly.

Thousands of ComEd customers have also lost power during the heat wave, making for a miserable situation.

Dorothy and Doris Gray returned to their North Side home Thursday after sleeping in their car due to their power being out.

“It was an adventure,” Doris Gray said. “It’s like I’m homeless with my rent paid.”

The City of Chicago is pleased with the way people are responding to the heat, but they want everyone to remember that heat stress is cumulative.

“it is extremely important to keep our body cool, and again, the research tells us that air conditioning is the most protective factor against heat-related illnesses,” said Dr. Vechara Couchair of the Chicago Department of Public Health.

But sometimes, you can’t choose your situations. On Thursday afternoon in 90-plus degree heat, many Red Line commuters had to stand outside as the CTA Red Line was delayed by melted tracks.

The CTA said the track defect forced all trains onto one track between the Cermak-Chinatown and Sox-35th stations.

“Before we got to Chinatown, there was like a 10 minute delay on the train,” said one commuter, A.L.

“About 20 minutes, which is unusual for this time of day,” said another commuter, Charles Sabree.

The Medical Examiner’s office says there could be several other heat-related deaths, but those cases are pending.