(This article, first published Monday, was updated Tuesday and Wednesday mornings with the latest records and forecast information.)
The Great Lakes and Northeast are witnessing some of the hottest weather they’ve ever experienced so late in the year.
The abnormal warmth comes at a time residents are normally bundling up in the frosty morning air and all the talk is the changing foliage. Instead, temperatures have shot up to 90 degrees all the way north of the Canadian border. In some areas, like Chicago, 90-degree heat toasted the region for an entire week.
Consider some of the incredible heat milestones set in recent days:
- Chicago hit 90 degrees for a seventh straight day Tuesday, its longest such streak so late in the season. Record highs were established on all seven of those days. Chicago hadn’t had such a long streak of 90 degree days since 1988 in the middle of summer (9 straight days July 27 to Aug. 4).
- Green Bay played its warmest home football game Sunday at Lambeau Field in Wisconsin, with a kickoff temperature of 89 degrees. It hit 90 four straight days ending Monday, which was its latest 90-degree day on record.
- Burlington, Vt., had its hottest day so late in the year by seven degrees Monday, hitting 92 degrees. It hit 90 degrees for a third straight day Tuesday, unheard of in late September.
- Buffalo hit 90 degrees on back-to-back days Sunday and Monday, its latest pair of consecutive 90 degree days on record.
- Minneapolis had three straight days at or above 90 ending Sunday, its longest stretch so late in the season.
- Milwaukee, which hit 95 degrees Friday, had its hottest day so late in the season by a week.
- Caribou, at the northern tip of Maine, hit 88 degrees Monday and Tuesday — its hottest days so late in the season. Tuesday marked the fourth straight day there in the 80s, its longest streak so late in the year.
- Ottawa, Canada soared to 91 Monday, its hottest temperature so late in the year by 7 degrees.
Interestingly, locations in Vermont and Maine were as warm or warmer than areas much farther south early this week. For example, Caribou’s mid-afternoon temperature of 88 degrees on Monday matched the reading in Tallahassee, Fla. Burlington, at 92 degrees, Monday was warmer than Washington, D.C., where the high was 91. Almost all of these locations were hotter than Phoenix, which had an unusual four straight days below 90 degrees.
Highs in the low 90sF Tuesday as far N as New Brunswick, Canada. Hotter than both Phoenix and Miami. pic.twitter.com/kHlk1MqHxo
— Jonathan Erdman (@wxjerdman) September 27, 2017
The hot weather came as the result of unusually strong heat dome, which developed last week over the Upper Midwest and drifted into the interior Northeast early this week.
After one more day of record-challenging heat in the Northeast Wednesday, strong cold front to the northwest will crush this heat dome, ending this summerlike fling.
This latest heat wave is the second of historical significance in this region this calendar year. In February, it witnessed another round of record warmth. Chicago set record highs on four straight days, climbing to around 70 degrees — its most pronounced early season warm spell ever recorded. And Milwaukee and Green Bay both set their all-time highs for February.
Milwaukee has now, in the same year, experienced its warmest weather ever recorded so early and late in the calendar.
The increasing prevalence of such warm weather extremes is exactly what we expect as concentrations of heat-trapping greenhouse gases rise in the atmosphere.