We're in the midst of an uncommon heat wave that feels like mid-July and is breaking records along the way.
Friday ushered in the first day of fall, but it was more memorable as the third-straight day of 90-plus degree temperatures, each a record for the date and the latest recorded since 2007. The string could continue as more heat is expected Saturday -- the record high is 91, set in 1937. Even the highest low temperature of 71 degrees set in 1891 could be threatened.
Could more records fall?
"It's not unprecedented but it's certainly rare and exceptional warmth," said Ricky Castro, meteorologist with the National Weather Service in Romeoville.
If the unseasonable heat isn't enough, allergy sufferers say a high mold count has added to the misery index. However, experts say there's no connection, although humidity may have encouraged mold growth and spores are being spread by winds.
Here are five weather items of interest:
• Stretches of three consecutive days of 90 degrees or higher this late in the year have occurred twice before: Sept. 30-Oct. 2, 1971, and Sept. 19-22, 1895. If 90-plus is recorded Saturday and Sunday, as predicted, that would be the most consecutive days this late in the year.
• The latest 90-degree reading in Chicago was Oct. 6, 1963, with a high of 94. The latest 95-degree or better day on record was Sept. 29, 1953, when it hit 99.
• Hoping for a frost? The earliest frost on record was Sept. 22, 1995, coincidentally the year of the deadly July heat wave. Average first frost is mid-October for the suburbs. The latest frost reported was Nov. 24, 1931.
• Unseasonable warmth will foster a large fall pollen season, according to Dr. Raymond Pongonis, an allergist at Advocate Good Samaritan Hospital in Downers Grove. "The main culprit in the fall is ragweed," he said.
• The highest above-normal temperature of any month was recorded in March 2012, which included eight of nine days between March 14-22 at 80 degrees or above.