The summerlike temperatures that continued through mid-September could result in the warmest September on record across the Midwest and the Northeast.
Even though some cooler and closer-to-average temperatures are expected through the end of the month, the surplus of abnormally high temperatures so far this month may be too much to overcome.
The result could be record-setting warmth in many major cities.
The warmest September on record for Pittsburgh was in 1961, when the average temperature throughout the month was 68.5 F. Through Friday, Sept. 26, the average temperature in Pittsburgh was warmer than that, at 70.3 F, about 5.2 degrees above normal for the month. Although near-normal temperatures continue through the weekend, highs are expected to soar near 80 F before the end of September.
A similar situation is setting up in New York City. The average temperature through Sept. 26 was 75.4 F, almost two full degrees above the record month in 1961, where the average temperature was 73.6
Record-challenging temperatures extend as far west as Minneapolis, where the average temperature through Sept. 26 was tied with the warmest September ever (in 1897) at 68.8 F.
Major cities in between, including Chicago, Detroit and Hartford are near, if not surpassing, their record warmest Septembers. Most are only a degree or two away from breaking the records as the month comes to a close.
However, a cold front moving through for the middle of the week could spoil these new possible records, right at the end of the month.
On Tuesday and Wednesday, a cold front diving down from Canada will bring behind it chilly airmass that will send temperatures below normal.
"The Upper Midwest and Great Lakes will be up to 10 to 15 degrees cooler Tuesday and Wednesday, than on Monday," Meteorologist Rob Richards said.
"In places like Minneapolis, Chicago and Detroit, this will make it feel more like fall," Richards added.
Autumnlike temperatures, however, are not expected to last very far into October.
"The thinking is that, with the strong El Nino in place, we are likely to see a continuation of the warmer-than-normal pattern of September into October from the Midwest to the Northeast," AccuWeather Senior Meteorologist Joe Lundberg said.
However, Lundberg warned this would not mean October would be without its cold spells.
"There will be a couple of notable cool outbreaks, including the one to start off the month of October, and likely another the following week," Lundberg added.
Lundberg and the collective team of Long-Range Meteorologists at AccuWeather will continue to monitor the pattern as the fall progresses, keeping an eye on the fall foliage that could be hindered by the extended warmth in the East.