The calendar may say October, but you would not know it from the thermometer. Record-breaking heat seared much of the country on Tuesday, including the Ohio Valley, the Northeast and the Southeast, even as Montana and Idaho were dealing with as much as 4 feet of snow from an intense winter storm over the weekend.

Highs in the mid-90s were expected on Tuesday in the Ohio cities of Cincinnati, Dayton and Columbus, shattering daily records that date back more than 135 years. Officials in Columbus closed the city’s schools because of the oppressive heat and humidity.

“We do not take this decision lightly,” Talisa Dixon, the city’s superintendent of schools, said in a statement. “The greatest challenge is not just the hot temperatures during the day, but how hot and humid it stays into the evening. Our schools simply cannot cool off at night.”

Farther east in the Washington and Baltimore areas, temperatures were running 10 to 15 degrees above average with humidity levels more like August than October. Some schools in Baltimore that lack air-conditioning were closed. Cody Ledbetter, a meteorologist at the National Weather Service’s office in Sterling, Virginia, called the weather “pretty rare.”

In New York, the forecast high for Central Park was 88 degrees for Tuesday and 90 degrees for Wednesday — almost 20 degrees above normal. “It’s a pretty remarkable margin,” said John Murray, a meteorologist at the Weather Service’s New York office.

The jet stream — the current of powerful winds that drives weather systems across North America — has been shifted farther south in the West, allowing wintry weather to move into the northern Mountain States. But it has been swinging northward over the middle of the country, keeping a cold front at bay to the north and allowing a large mass of hot, humid air to stay in control in the East.


As a result, nine states in the Southeast are expected to see temperatures in the mid- to high 90s on Tuesday and Wednesday, setting records for the month. Experts say the warming of the global climate can be expected to make extreme weather of all kinds occur more often, including unseasonable temperatures.

“This level of heat is not uncommon in July and August,” said Evan Webb, a meteorologist at the Weather Service’s office in Louisville, Kentucky. “For October, this is uncommon. It’s not out of the realm of possibility for Louisville to reach 100 degrees.”

The heat wave caps an unusually rain-free period in many areas. September was the driest month ever recorded in Kentucky, with just 0.04 inches of rainfall reported.

“Heat and drought go hand in hand,” said Victor Murphy, the Southern regional program manager for the Weather Service. “The biggest impacts are on agriculture. No rainfall and record temperatures are not a good combination. They’re susceptible to crop failure.”

The record-breaking snowstorm over the weekend in Montana was just as unseasonal as the heat wave elsewhere. Power was knocked out in many areas of the state, several major highways were closed and farmers lost unharvested crops.

The excessive heat across the South and the East is not expected to last much longer. As the jet stream shifts back to a straighter path, a cooler air mass is forecast to move south and east, bringing many areas some rain as well as welcome relief from the heat.

“The cold front comes in on Friday, bringing temperatures to near normal over the weekend,” Murphy said. “There’s good news on the horizon.”