Colin King, with Saskatchewan's Emergency Management department, said 1,000 military personnel were arriving from bases in Shilo, Man., and Edmonton.
About 600 are to receive basic wildfire training and will likely be on the ground Wednesday alongside another 600 firefighters.
The remaining soldiers are to work in support roles such as helping with equipment and getting food and water to fire crews.
King described the fire situation as "critical" and said people evacuated from more than 50 communities wouldn't be returning soon.
"The threat has not been reduced in any of those communities. We are advising all community leadership to remain out until it is safe," he said.
As of Monday evening, the most significant of 112 fires burning in the province was north of La Ronge, one of the largest communities in north. Mayor Thomas Sierzycki issued a fire update on Twitter about 8 p.m. local time saying the flames were just 1.5 kilometres from residential areas.
Residents were evacuated on the weekend from the town, as well as neighbouring Air Ronge and the Lac La Ronge Indian Band.
Fires and thick smoke forced others in the north to start leaving their homes 11 days earlier.
Flames have destroyed about a dozen homes, remote cabins and other buildings in Montreal Lake, Weyakwin and Wadin Bay. One building also burned north of La Ronge.
About 300 square kilometres are burning in what officials are calling high-priority fire zones, about 10 times the yearly average.
Scott Wasylenchuk with the Provincial Fire Centre had some good news, however. An area near La Ronge burned in an old forest fire is acting as a natural barrier and wind was expected to shift flames away from the town.
"Which means some of the fire lines closest to the community won't be as hot and we'll be able to get on them and make good progress," he said.
Premier Brad Wall, who visited La Ronge last week, said he's glad soldiers are on hand to help and he's not worried fire will spread into the town.
"Right now we're in a pretty good spot ... We're feeling cautiously optimistic after a difficult weekend."
Nearly 700 evacuees from La Ronge were being housed in Cold Lake, Alta. The Alberta government had said it was preparing to receive up to 5,000 after centres in Saskatoon, Regina, Prince Albert and North Battleford were filling up.
"We always have problems with fires here and there but never in my lifetime can I remember it being this bad," Darlene Studer told radio station CJME, after convincing her 90-year-old father to leave his home in La Ronge.
Karri Kempf with Saskatchewan's Social Services Ministry said slightly more than 7,000 have registered as evacuees and she estimates another 2,000 others are staying with friends and family.
Fires are also burning in other Western provinces.
In Alberta, 200 people remain out of their homes on the North Tallcree First Nation.
Environment Canada issued special air quality statements for much of Saskatchewan and parts of Manitoba, Alberta and British Columbia.
— With files from CJME
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