Winter Keeps Grip on East, Midwest; Two Towns in N.Y. Record 37 Below : Weather: In Minneapolis it’s too cold for a parade. Boston opens shelters for the homeless during the day. Diesel fuel turns to jelly.

The season’s strongest blast of frigid air dropped temperatures to nearly 40 below zero Monday, thickening diesel oil to jelly in truck fuel tanks and even forcing hardy Minnesotans to concede it was too cold for a parade.

“People can freeze to death in this kind of weather,” said Kelley Cronin, director of Boston’s Emergency Shelter Commission, which opened city-run shelters Monday that normally are closed during the day. The windchill made it feel like 15 below zero.

The cold forced cancellation of Monday night’s Holidazzle parade in downtown Minneapolis, part of a series of celebrations held since Thanksgiving to attract holiday shoppers to downtown.

“It’s an eight-block parade and along the route the families and children were bundled up in blankets and were out there being spirited Minnesotans, but we didn’t want to put them through that again tonight,” parade director Todd Klingel said.

The windchill during Sunday night’s parade was 11 below and only a few thousand spectators turned out. Anywhere else, everyone would have stayed home, but Minnesota, with its Viking heritage, has a mania for winter sports and winter carnivals.

Shelters for the homeless in many cities were filled to capacity. Police in some cities gave homeless people rides to shelters. American Automobile Assn. chapters got thousands of calls for help from motorists with dead batteries.

*

At least two deaths were blamed on the cold.

An 86-year-old woman died of exposure at Westfield, Ind., after she apparently slipped and fell while walking her dog Sunday, the county coroner said Monday. And in Maryland’s Anne Arundel County, police said a woman found dead Sunday morning in a cemetery died of exposure.

Temperatures fell to record lows for the date Monday morning, from 30 below zero at Bismarck, N.D., to 9 below at Binghamton, N.Y., and 29 above at Melbourne, Fla., the National Weather Service said.

Unofficially, the small community of Embarrass, Minn., reported a low of 35 below zero.

Northern New York state went down to 37 below at Gouverneur and Canton. Hikers setting out for the woods at Lake Placid were warned of windchill factors down to minus 75, said Chrissy Ford, coordinator of the Adirondack High Peaks Information Center.

It’s not just a brief cold snap for the Northeast.

“It looks like it’s going to last. There really isn’t much relief in sight, at least through the rest of the workweek,” said weather service meteorologist Charles Ross in Portland, Me.

Temperatures in northern Maine fell to 17 below at Houlton and state troopers said trucks were halted along major highways because their diesel fuel turned to gel.

The cold boosted the threat of fires as people strove to keep warm, and it also made firefighting more difficult.

“You don’t know whether the hydrants are going to work,” said Steve MacDonald, a spokesman for the Boston Fire Department. “Everything freezes up when you’re spraying water, right down to the button on your two-way radio.”