The forest fire hazard is now high to extreme in the Sioux Lookout and Nipigon districts.
Six new fires sparked in the Sioux Lookout area on Canada Day.
One is being held, while two others are under control.
The Ministry of Natural Resources says additional crews are being sent to the area.
The largest fire currently burning in northwestern Ontario is Nipigon Fire #23 at 4,600 hectares.
Sprinkler units are now being set-up to protect nearby property.
