A third straight day of record-setting heat is forecast for today -- just the third time since records were kept that we've had three days in a row in the 100s.

Friday’s forecast calls for a high between 100 and 105 degrees, with a heat index between 105 and 115, National Weather Service meteorologist Tim Seeley said. The record is 99 degrees, set in 1988.

“It’s a pretty good bet we’re going to set a record high for the third day in a row,” he said. Only two other times in Chicago’s record books have there been three straight days of temperatures in the 100s: July 3-5 in 1911 and Aug. 4-6 in 1947.

We even have a shot at four straight days in the 100s, something that has never been recorded in Chicago.

The forecast calls for a high near 100 on Saturday before a cold front brings temperatures down to the 80s on Sunday.

An extreme heat warning for the Chicago area had been set to expire at 6 p.m. Friday but now has been extended to 4 p.m. Saturday. The weather service said the heat index -- how it feels -- could climb to 116 on Friday and will hover at 105 on Saturday.

The Cook County medical examiner's office has linked two deaths so far to the heat and is investigating four others.

Wednesday’s high of 102 matched the record high set in 1911, and Thursday's high of 103 surpassed a thee record of 102, also in 1911. Friday’s temperatures could flirt with the all-time high temperature in Chicago – 105 degrees in 1934 – but passing that mark isn’t likely, Seeley said.

As of 8 a.m., it was 87 at the city's official recording station atO'Hare International Airport, with a heat index of 94; 88 at Northerly Island, index of 99; 86 in Waukegan, index of 90; 86 at DuPage Airport, index of 94; 85 in Lansing, index of 93.