The City of Yellowknife is warning the public to exercise caution on lakes in the city, particularly Frame Lake near the Co-op underpass.
Officials say the ice in that area is thin and should be avoided by pedestrians and snowmobilers.
They are also reminding the public that as temperatures increase ice will begin to weaken.
Signs of weak ice include water covering the ice and a change in ice colour from clear to milky.
Areas around protruding rocks or objects should also be avoided.
Residents across the territory should exercise extreme caution when heading out onto the ice at this time of year, particularly with the record mild temperatures the NWT has experienced this spring.
The ice warnings come amid reports that the Dettah Ice Road may close for the season as early as Thursday.