Decent weather week for Montreal - record heat in BC

A quiet weather patter is setting up for the week ahead across southern Quebec and Ontario. Sunshine today will allow temperatures to warm to near 26C (79F). There is a little humidity leftover from the 13mm of rain on Sunday, but it should remain clear and dry. Weak low pressure along with a frontal boundary will cross the St. Lawrence Valley on Tuesday with scattered showers and perhaps a thunderstorm. It will be another mild day, around 24C (76F). The frontal passage will allow for some September like air to stream across the Great Lakes with a couple of days of natural air conditioning forecast. Temperatures will be in the low to middle teens at night and perhaps 21C (70F) during the day from Wednesday into Friday. As the high drifts offshore into the Atlantic, much warmer and increasingly humid air will move into southern Quebec by next weekend with sunshine and highs in the upper 20's to near 30C (86F) by Saturday.

Dense smoke from forest fires like this one near Kakisa in the NWT is lowering air quality across western Canada. (CBC News)

WESTERN HEATWAVE

The big weather news this week will be the hot and humid weather across the Pacific Northwest, BC and Alberta. Parts of interior B.C. near Osoyoos hit a record 40C (104F) on Sunday, Lytton also set a record at 41.1C (106F) with hot air streaming north from the deserts of the southwestern US. The hot weather will prevail all week with forecast highs from 35C to 40C (95-102F) through Friday. The hot, windy weather and lightning strikes have increased the forest fire threat with nearly 140 fires burning in the Northwest Territories alone. Over 50 fires are burning in British Columbia. The fires have sent a plume of smoke south and east across portions of Alberta, Saskatchewan and Manitoba over the last week producing very poor air quality. The record highs forecast this week in B.C. will not help the situation.