In some parts of Canada, the end of summer vacation is bringing some of the hottest temperatures of the year.

In other areas, it’s bringing weather more typically experienced in December than during the last week of August.

Some B.C. communities saw temperatures dip near or below the freezing mark Monday morning. A temperature of -1.5 C was recorded at Burns Lake at 5 a.m. One hour later, the temperature in Prince George dipped to 0 C.

The cold snap marked Prince George’s second unusual weather phenomenon in eight days, following the ash-filled skies that had shrouded the city from the sun as smoke from some of the province’s hundreds of active wildfires drifted over the region.

Temperatures in the low single digits were also reported Monday in some areas around the B.C.-Alberta border. Traffic cameras captured snow falling on Alberta’s Highway 1 near the community of Canmore.

It was a very different story in Eastern Canada, where heat warnings were in place for most of southern Ontario and parts of southern Quebec.

Environment Canada warned that cities including Toronto, Montreal and Hamilton would see daily highs at or above 30 C through Wednesday, with humidex values around 40.

Tuesday was expected to be especially hot and humid in the Montreal area. Cooler temperatures were expected later in the week, with a slight warmup in the forecast for the Labour Day weekend.

Authorities warned that parents should ensure to keep their children hydrated and away from prolonged exposure to heat to help prevent medical emergencies.

Also considered particularly at risk for heat-related illnesses are seniors, pregnant women and people with chronic illnesses, although Environment Canada was warning all people in areas under heat warnings to drink water and try to avoid outdoor activities during the hottest periods of the heat wave.