High humidity and precipitation have been helping crews get a handle on the more than 100 fires active in the region.
But the thunderstorms bringing much-needed moisture to the area are also producing lightning strikes, which have sparked several new fires.
Now that the skies have cleared, the situation could worsen again, said Mitch Miller, a fire information officer with the Ontario Ministry of Natural Resources in Dryden.
We've got drought-like conditions, he said in a phone interview with The Weather Network Friday. I think we're going to see every day now an increase in fire activity.
This has been Ontario's most active fire season in recent memory. Fires have so far consumed some 500,000 hectares of forest -- an area almost the size of Prince Edward Island -- and the season isn't over yet.
It's still the middle of the game here, Miller said. We've got a long way to go to get to the end of this fire situation.
More than 3,500 people have been forced to leave the area due to thick smoke. Communities across Ontario have stepped up to host the evacuees, including Greenstone, Ignace, Arthur and even Ottawa.
According to the Ministry of Natural Resources, 2,000 fire personnel remain engaged in the battle against the fires. More than a quarter of them come from other provinces, including Alberta and British Columbia.
On Friday, Ontario premier Dalton McGuinty surveyed the fire-stricken area, making stops in Thunder Bay and Dryden to meet with MNR officials, volunteers and evacuees.
McGuinty said the province is doing everything in its power to protect lives and property.
Much of northwestern Ontario has been declared a restricted fire zone, which means no open burning is permitted.
Emergency area orders restricting travel on roads and waterways also remain in place around several Sioux Lookout-area fires.
With files from the Canadian Press and the Ontario Ministry of Natural Resources.