The hottest July 4 on record? 100 in forecast, worse Thursday

Temperatures are expected to climb to 100 degrees today and could threaten the all-time high for the recorded history of Independence Day, which was 102 set back in 1919.

Although Thursday is expected to be the hotter of the next two days, a heat advisory is in effect until 9 p.m. today as the humid conditions could produce a heat index of up to 110 degrees, according to the National Weather Service. A 30 percent chance of thunderstorms is possible in the late afternoon.

Temperatures are expected to climb to 102 on Thursday, and additional heat warnings are expected to be activated for Thursday and Friday. Temperatures could reach 100 again on Friday, according to meteorologists.

The average high for July 4 is 84 degrees.

The high at O'Hare International Airport peaked at 95 Tuesday, but temperatures were fairly steady into the night and as of about 10 p.m. it was 87 degrees at the airport.

Forecasters said it was possible the area would reach 100 today though Friday, which would tie the record of consecutive 100 degree days — three, set July 3-5, 1911.

High temperatures are expected to be around 90 Saturday before dropping into the mid-80s on Sunday.

In the 140 years of records, Chicago has had 62 days with a temperature that reached triple digits, an average of about one 100-degree day or worse every 2.3 years. Chicago hit 100 on June 28 this year, and the last time before that the area reached 100 was July 24, 2005, when the high peaked at 102.

The record at a Chicago observatory was set on July 24, 1934, when it was 105 degrees.