Hot, dry weather to start the weekend, adding to wildfire risk in southern Alberta

Heat warnings continue across the southern portion of Alberta, Saskatchewan and British Columbia, with both daytime high and low temperatures expected to exceed normal thresholds.

Environment and Climate Change Canada (ECCC) will issue a heat warning for most of Alberta when daily maximum temperatures are expected to reach at least 29 C along with daily minimum temperatures of at least 14 C for at least two consecutive days.

For details on heat warning threshold criteria from ECCC click here.

Heat warnings (pink) and air quality advisories (grey) issued by Environment and Climate Change Canada on Aug. 1.

The source of this heat is a ridge of high pressure that extends to the southern U.S. but unlike the stationary ridge from July, this ridge will track to the east by the middle of the weekend.

As the ridge does move out, convective weather (thunderstorms) are possible in central and southern Alberta, which is less than ideal with an elevated wildfire risk.

As of 6 p.m. on Thursday, all of southern Alberta and southern Saskatchewan were under an "extreme" risk according to the Fire Danger Relative Index.

This is an evaluation of a number of potential risks but can be summarized in three parts: How likely it is for a wildfire to start, how difficult it would be to extinguish a wildfire if one does start and how much damage could be done.

Since this is a relative index, it can change considerably from day to day due to weather conditions (and other factors).

The forecast outlook for Friday shows a smaller region in southern Alberta under an extreme risk with an increased risk (to "high" for most of Alberta).

In Calgary, daytime highs will drop to below-seasonal temperatures by Monday, and rain is possible from Sunday until Tuesday.