The spring storm that's roaring across three provinces is continuing Thursday, and in northwestern Ontario, power has been out and highways have been closed for much of the day.

The weather system that originated in the Prairies is making its presence felt across the Ontario region, with the Sioux Lookout and Red Lake areas expecting up up to 20 centimetres of snow, while other areas will likely see up to five cm.

Environment Canada meteorologist Gerald Cheng said conditions in areas along the north shore of Lake Superior are improving, but places near the Manitoba border are still dealing with snow and low visibility.

Cheng said snow will continue to fall throughout Thursday, but should get lighter throughout the day.

"We're over the hump and things will get better from here onward," he said. "Spring is a transition season, and that is important to remember. This is the season when the very cold air mass and the warmer air masses fight it out, especially over Ontario and northwestern Ontario in particular."

Highway 17 between the Manitoba border and Shabaqua had been closed from overnight Wednesday into early Thursday afternoon, but has since reopened. Highway 502, the corridor linking the Fort Frances and Dryden areas, had also been closed but reopened in the afternoon. Highway 599 from Highway 17 to the end of the roadway in Pickle Lake remained closed Thursday afternoon.

The Keewatin Patricia District School Board has closed all of its schools. Five rural schools in the Thunder Bay area — Crestview, Gorham and Ware, Kakabeka Falls, Valley Central and Whitefish Valley public schools — are closed. The Atikokan High School and North Star Community School in Atikokan are both closed.

Student transportation service providers across the region have parked school buses on Thursday.

The City of Kenora has shut down its municipal transit service for a second consecutive day.

About 3,000 customers in the Thunder Bay area are without electricity as of Thursday morning, according to Hydro One's online storm centre map. Outages in the Fort Frances area are affecting more than 1,000 customers.

Hydro One spokesperson Alicia Sayers said the heavy snow and strong winds are responsible for the outages.

"Our crews are doing their absolute best to get the lights back on."

The Lake of the Woods Museum and Douglas Family Art Centre in Kenora are both closed on Thursday due to the weather conditions.

In Sioux Lookout, a 30-cm increase in the snow depth was recorded on Thursday compared to the previous day, Cheng said.

Sioux Lookout Mayor Doug Lawrance said road crews have been prioritizing clearing main roadways in the municipality.

"Crews have been working. There's lots of work to do. As they work, more snow falls," Lawrence said.

"It's a grind on top of many other things this winter. This snow isn't going to disappear quickly. It's going to extend our snow on the ground, I'm sure through the end of April."

It was a snowy and slushy start to the morning for Brad Balec, a newspaper carrier in Thunder Bay.

"I wore hiking boots because I didn't want to be slowed down by my big winter boots, but I'm regretting that decision. I have a lot of snow down them," he said.

Cheng said normal seasonal temperatures in Thunder Bay should be 9 C, but the Easter weekend will have temperatures around 0 C.

John Jakobs, who lives about 16 kilometres north of Vermillion Bay up Highway 105, said he woke up to about 30 cm of snow.

Jakobs works as an angling guide and said that on this date last year, he was in a boat fishing on the water.

"[This year] I'll be ice fishing for another few weeks," he said, adding people are hoping to have open water for when outdoors tourists typically start arriving.

"Everybody's hoping for at least open water, and that would be the third Saturday in May when the season officially opens. We have six weeks of hoping the ice goes away."