Concern is growing for a missing Whitby, Ont., high school teacher who has not been seen since early Monday morning, as temperatures are expected to drop below freezing tonight.

Jeffrey Boucher, 52, was reported missing Monday, after he failed to return home from his morning run, Durham Region Police said in a statement on Tuesday.

Boucher, who teaches at Bowmanville High School, hasn't been seen or heard from since.

In a press conference, police said they're worried Boucher may have slipped on the ice and injured himself while running somewhere along his route. Boucher's cellphone was left at home.

"Our strongest lead is that he followed his regular routine and went for his morning run,” Sgt. Nancy Van Rooy told reporters. "There is not any suspicion of foul play at this time."

On Tuesday, volunteer rescue crews joined Durham police to scour an icy dense trail in a Whitby conservation area, where Boucher is known to run.

No one saw Boucher leave the house on Monday, but his wife, Kirsten Boucher, believes he went on his regular 6 a.m. jog.

"I don't know which route he took but after having told him how icy all the sidewalks and trails were, honestly, the only safe place to run is on the road and if he had been on the road, somebody would have found him by now," Boucher's wife told CTV Toronto.

According to Boucher's running partner, the high school teacher is a "routine guy" who goes out for an approximately 45-minute run around 6 a.m. nearly every morning, before heading to work. Boucher is known to run long distances and change his route often.

"He's home by 7, showered and everything. He leaves for work around 7, every single morning," Boucher's daughter Bettina told CTV Toronto.

A command post has been set up in the vicinity of his home near Brock Street and Taunton Road, across from a wooded area. Police say they're concentrating efforts on the nearby Heber Downs Conservation Are.

"We are concentrating on the town of Whitby, but we are keeping in mind that he's an avid runner," Van Rooy said. Police are also searching residential neighbourhoods and commercial properties within a 10- to 15- kilometre radius from his home.

A police helicopter conducted an aerial search using infrared technology, and a canine unit was brought in to assist with the ground search, but so far police have been unable to locate the teacher.

The Ontario Volunteer Emergency Response Team (OVERT), a search and rescue unit with specialized training and equipment, also joined the search Tuesday morning.

"We have upped our extensive coverage," Van Rooy told the media. "We feel very confident we are doing everything we can with the resources we have."

In a message on Twitter, Boucher's daughter thanked the volunteers: "Miss my dad. Its been 24 hours. Thanks to everyone for their support."

Durham police are requesting homeowners in Whitby to check their property for signs of the missing man. Investigators say they do not know what Boucher was wearing during his run or how many layers he had on. Environment Canada expects temperatures in Whitby to drop to -3 C tonight. Periods of light snow are expected after midnight.

Boucher is described as white, six feet tall and 180 pounds with glasses and short grey hair.

Van Rooy urged the public to come forward with any tips: "We have not had many leads."

Anyone with information is asked to call police at 1-888-579-1520 or Crime Stoppers at 1-800-222-TIPS (8477).

With files from CTV Toronto