Autumn heat wave could topple centuries-old records in the Midwest
A late-season heat wave will send temperatures to record-challenging territory across a swath of the north-central United States into the first week of October, AccuWeather forecasters say.
While the warmth would be typical for the middle of summer, it is unusual for early October, with temperatures expected to be 10 to 20 degrees Fahrenheit above historical averages. This will result in high temperatures well into the 80s and even near 90, threatening daily records that have stood since the 1800s.
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"A sustained period of record-challenging highs will last into the first few days of October in the Twin Cities," said AccuWeather Senior Meteorologist Dan Pydynowski. "A forecast high in the mid-80s on Oct. 1 is on par for the historical average in mid-July, during the peak of their warmth in the summer months."
In Minneapolis, the record highs of 87 on both Saturday and Sunday were set 126 years ago, in 1897. After breaking the first of those records with a high of 88 on Saturday, the mercury is expected to rise to the same level on Sunday.
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Across the region, high temperatures are typically in the 60s and lower 70s entering October, but some areas can approach record territory near 90 for multiple days. As in the case of Minneapolis, some of the records that will be challenged by the heat wave have stood since the late 1800s.
The number of record highs that will be in jeopardy due to the heat wave through early week is in the dozens, including the cities of Des Moines; Fargo, North Dakota; Madison, Wisconsin; Omaha, Nebraska; and Wichita, Kansas.
The near-record warmth will last through at least the start of this week when a change in the pattern will usher in cooler air to replace the record warmth.
The warm spell will be good news for those pining for some last-minute outdoor summer fun, despite the days marching deeper into fall. Activities such as playing golf, attending sporting events, spending time on the lake or attending fall festivals will occur amid summertime warmth.
There are some drawbacks to the warm, dry weather; however, that could have negative trickle-down effects deep into the autumn months, according to AccuWeather experts.
The late-season warmth can delay the peak of fall foliage, slowing how quickly leaves turn color. This will especially be the case over the Lower Midwest, where little change has occurred so far.
According to recent foliage reports, 'moderate' to 'high' color was already occurring over portions of the Dakotas, Minnesota, Wisconsin and the Upper Peninsula of Michigan; however, only 'low' color was being observed farther south from much of Iowa into portions of Nebraska, Missouri, Illinois and Indiana. The warmer weather will likely slow the advance of the more colorful leaves across this region.
Accompanying the warmth will also be a largely dry weather pattern over the region that will last for nearly a week. That will have negative implications for agricultural and some commercial interests amid a long-lasting drought, according to the latest U.S. Drought Monitor.
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In almost a carbon copy of last year, water levels on the Mississippi River and most of its major tributaries have plummeted from late in the summer and into autumn due to expanding drought.
"Much of the Mississippi River watershed has been experiencing worsening drought conditions in recent weeks," said AccuWeather Senior Meteorologist Alex Sosnowski. "This has sent water levels plummeting."
According to CNN, the water levels on the Mississippi are near or at record lows, and that is causing saltwater from the Gulf of Mexico to move up the river, polluting drinking water. This is the second autumn in a row when low water levels on the Mississippi River impacted barge traffic ahead of the annual fall harvest across the nation's midsection.
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"The low water levels are also creating problems for barge traffic at a busy time of year for the transport of grains downriver," added Sosnowski. "Levels may continue to ratchet down even further until a wetter pattern takes hold."
Early Friday morning, the river level at Memphis, Tennessee, dipped to its third lowest stage on record (-10.64 feet) according to the United States Army Corps of Engineers. Only the severe drought from last October (-10.81) and July of 1988 (-10.70) were lower.
There is no guarantee that enough rain will fall during the mid-autumn to make a substantial difference in water levels on the middle and lower Mississippi River, Sosnowski cautioned. However, Accuweather meteorologists are highlighting a wave of rain and thunderstorms could impact the south-central U.S., and perhaps parts of the Mississippi River Basin.
Those enjoying time outdoors in this warm weather will also want to be wary of typical summertime dangers extending into the fall, including how hot that it can get inside cars when the sun is out and the risk of sunburn if outside for an extended amount of time.
AccuWeather meteorologists say the heat will break around the middle days of the new week but that the cooldown will come at the expense of some rain and perhaps severe thunderstorms.
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