Thursday will be Calgary's hottest day of the week

Heat warning in place for Calgary Calgary is under a heat warning. Gina Martin has a look at the five-day forecast from the Sky Watch Weather Centre.

The city of Calgary remains under a heat warning Thursday, along with the majority of southern Alberta.

As a ridge of high pressure continues to linger over parts of western Canada, more communities closer to the U.S. border have now been included into the heat warning criteria, including Lethbridge.

Thursday, Calgary will experience a lot of sunshine with a high of 31 C and a UV index of 7 or high.

Daytime highs take a slight dip on Friday and Saturday, but will continue to peak into the high twenties.

This heat event differs from the one we experienced back in July in the sense it’s not flanked by two low-pressures systems, allowing the jet stream to have more movement.

That means this ridge of high-pressure will likely start to break down as we get into Sunday and the holiday Monday.

Temperatures will still be nice, but a lot closer to seasonal, if not slightly below normal.

As the jet stream starts to move on Sunday, models indicate the clash of warm and cool air masses could create the potential for thunderstorms in southern Alberta.

Right now, the risk for active weather on Sunday is at 40 per cent with more clouds and cooler temps settling in by next week.

Until then, the fire danger rating remains extreme for the south half of the province.