The cold front that is expected to whisk Hurricane Maria back out to sea after it nears North Carolina will gradually trim the summerlike warmth out of the midwestern and northeastern United States this week.
Friday marked the official start of autumn, but summer decided to hang around longer across the eastern half of the nation.
Monday will bring yet another day of temperatures soaring well into the 80s and lower 90s. Moderate humidity levels will create slightly higher AccuWeather RealFeel® Temperatures.
Temperatures will be held down a few degrees east of the Appalachian Mountains on Tuesday and Wednesday. However, an increase in humidity as Maria approaches will make the air feel just as warm as Monday’s highs.
Typically in late September, temperatures top out in the 60s in northern New England and the upper Great Lakes to the 70s elsewhere in the Northeast and Midwest.
Air flowing in from the Atlantic will keep Boston and the rest of the immediate East Coast cooler than inland areas.
However, beachgoers will need to use caution as Maria will cause surf and the threat for rip currents to gradually build to dangerous levels for swimmers and operators of small craft through midweek.
For those who have already put away window air conditioning units and/or are looking for true fall weather, a cold front will bring relief later this week.
"The same cold front responsible for eventually steering Maria out to sea will be the front that breaks this streak of warmth across the Midwest and Northeast by the end of the week," AccuWeather Senior Meteorologist Dan Pydynowski said.
The front will begin to push into the central Great Lakes on Wednesday, ending what is expected to be a seven-day stretch of 90-degree heat for Chicago.
The cooler air will continue to advance to the south and east, trimming temperatures and humidity values along the I-95 by Friday. The front will also slash sticky air out of the South, down to around the I-20 corridor, to close out September.
Highs later this week behind the front throughout the Midwest and Northeast will be 10-20 degrees below what will be recorded on Monday.
Despite whisking Maria and the summer warmth away, the front will not dramatically end the dry streak that has unfolded amid this warm spell in most areas.
While raising the risk for flooding across the Plains, the front will struggle to produce meaningful rainfall as it crosses most of the Midwest and Northeast.
The exceptions will be around Lake Superior and the St. Lawrence Valley. If Maria tracks close enough to North Carolina, its moisture may interact with the front to cause an increase in showers and thunderstorms along the Northeast coast.
Abnormally dry to moderate drought conditions are occurring from the mid-Mississippi Valley to the lower Great Lakes, according to the U.S. Drought Monitor.
“If Chicago does not receive any more rain this month, it would be the fourth driest September on record,” AccuWeather Meteorologist Brett Rathbun said. “Chicago has only received 0.32 of an inch of rain this month.”
In the front’s wake, a reinforcing shot of cooler air may be accompanied by showers across the Great Lakes but is likely not to produce a significant amount of rain.
Impressive statistics set as summer warmth hangs on
This extension of summer is actually proving to be the hottest stretch of weather this year in the Midwest.
"Many nighttime lows in the Midwest have been near or even above-average highs for late September," AccuWeather Meteorologist Bill Deger said. This includes Chicago, where temperatures have only dropped to the lower 70s the past few nights.
"This stretch of 90-degree heat in Chicago is now the longest this year, surpassing the streak from June 10-12," AccuWeather Meteorologist Matt Greene said.
Chicago is in the midst of its second latest streak of three or more consecutive 90-degree days on record. The stretch that spanned Sept. 30 to Oct. 2 in 1971 sits at the top spot.
Saturday's high of 95 F in Chicago also tied June 12 as the hottest day of 2017 and marks the latest day in recorded history when a given year's hottest temperature was registered.
It is not just Chicago that is sizzling in the year's hottest weather.
Before temperatures are trimmed later this week, Pittsburgh is expected to record 12 consecutive days of highs in the 80s. The previous longest so far this year was the 10 days spanning late June to early July.
Until the summer warmth is erased later this week, daily records will continue to be challenged or broken in the Midwest and Northeast. Some of these records date back to the late-1800s.
People should exercise caution and restrict strenuous physical activity during the hottest conditions.
"Intake of non-alcoholic fluids and frequent breaks are a must under these conditions to avoid dehydration, heat exhaustion and heat stroke," AccuWeather Senior Meteorologist Alex Sosnowski said.