Records continue to fall during the mid-March heat wave, as temperatures reached 80 degrees for the fifth straight day, and could continue the streak through Wednesday.
"There's extremes in weather, but seeing something like this is impressive and unprecedented," said Richard Castro, a meteorologist with the National Weather Service.
Sunday afternoon's 81 degrees continued the record string of 80 degree days in March, which was previously just two, set in 1986.
The earliest time the Chicago area had four consecutive days in the 80s was April 14-17 in 1976. Data for the earliest streak of five days was not available Sunday night.
"This stretch would be rare for April in this area," Castro said. "To see eighty-plus like that is not even a normal occurrence in the month of May."
Before the heat wave, there had only been 10 March days on record that reached 80 degrees, and on average Chicago would see one 80 degree day in March every 14 years.
Following an abnormally warm winter, the latest record-breaking streak started on Wednesday when temperatures reached 81 degrees, and remained in the 80s for more than six hours that day. The average for March 14 is 46 degrees, and for March 18 is 47 degrees, according to the weather service.
"it's extreme and unprecedented," Castro said.
The monthly average for March is 37.9 degrees, and as of Sunday, the average at O'Hare for the month is 49.3 degrees and expected to rise.
The forecast for each of the next three days calls for temperatures that could tie or break record highs each day, which will bump the monthly average above 50 degrees.
"With more days like this, that number is just going to continue to warm," Castro said.
Looking further into the spring, the outlook has a greater than normal probability for abnormally warm temperatures to continue, according to meteorologists.
"At least into April, this is going to continue," Castro said.
Monday's high is expected to reach the upper 70s, but it is possible that it could hit 80, according to meteorologists. The record for March 19 is 78 degrees.
Tuesday will likely break the record, with forecasts calling for highs in the lower 80s, and the previous record of 76 degrees. On Wednesday highs will reach the upper 70s, with the previous record of 77 degrees.
On Thursday the streak, if it reaches eight, will likely end with highs predicted in the upper 60s, and a previous record high of 79 degrees.