Up to 80 mm of rain is forecast to have fallen in some parts of the Dehcho by the end of Monday, meteorologists said in an early-morning warning.
Monday was Yellowknife's all-time hottest day, meteorologists say, reaching a high of 32.6C – fractionally warmer than a record set more than 30 years earlier.
A heat warning has been issued for parts of the Sahtu and Beaufort Delta starting Tuesday and lasting until Thursday.
A three-day heat wave is expected to impact Fort Liard, Fort Simpson, Wrigley, Nahanni Butte, Sambaa K'e, and Jean Marie River.
Preliminary data from Fort Smith's airport weather station suggests the NWT's all-time temperature record has been broken. At 3pm, Fort Smith stood at 39.6C.
Yellowknife, Behchokǫ̀, Hay River, Fort Smith, and Fort Resolution all experienced power outages on Wednesday. Some were blamed on lightning strikes.
A severe thunderstorm capable of producing "nickel-size hail and heavy rain" is bearing down on Fort Liard, forecasters said on Tuesday afternoon.
As some parts of Canada set heat records of more than 45C, Yellowknife residents woke on Tuesday to a heat warning. Here's how those warnings are issued.
Fort Smith is expected to reach at least 37C on Wednesday this week, forecasts suggest. It would be the town's warmest weather in 70 years.
A recent study is revealing more about the science behind the aurora and how the northern lights may differ from their southern cousins.
Hay River, Enterprise, and Fort Smith are being warned to expect persistent, heavy rain throughout Wednesday and into Thursday.
Federal forecasters have issued a severe thunderstorm watch for the Alberta-NWT border, Fort Smith, Fort Resolution, and Highway 6.