That means the general population should consider reducing strenuous activities outdoors, and children, the elderly, and those with respiratory conditions should take additional precautions.
High values are forecast to persist until Wednesday evening when a cold front moves across the region and is expected to clear some of the smoke.
There are currently 160 fires burning throughout the Northwest Territories.
Bill Mawdsley, director of forest fire management with the N.W.T. Department of the Environment, says there are currently no people in harm's way from any of the fires and no plans for any evacuations.
Officials with the Northwest Territories Power Corp. said a widespread power outage that hit Yellowknife, Hay River and Behchoko on Tuesday was not related to the forest fires but was caused by lightning strikes.
The fires were causing other problems, however, including intermittent road closures and the destruction of some fibre optic cables. Highway 3 from Fort Providence to Edzo was closed Tuesday night due to heavy smoke.
On the territories' fire information website, so many people tried to access a "live fire map" that it crashed.
"Over the last 14 days, over one million people have accessed the map," officials said on the territories' Facebook page. "This has had a huge impact on how fast information can be accessed not only by the public but also by our fire personnel that use the system. We have temporarily shut down the public map to see if we can increase the performance for fire management."
In the Sahtu region, a fire has been burning about 12 kilometres from a Husky Oil camp, but officials say there is no current threat to the camp or its workers.
There has also been a mixed blessing in the weather that has been hitting the area. Thunderstorms were bringing heavy downpours in some regions, but were also increasing the number of lightning strikes in drier areas.