Environment Canada has issued a heat warning for many parts of southern B.C. as temperatures are expected to climb from Wednesday through Sunday.
The warning, issued Tuesday, is in effect for Metro Vancouver, the Southern Gulf Islands, Howe Sound, Whistler, Sunshine Coast, Greater Victoria and inland and east Vancouver Island.
Temperatures ranging from 34 C to 38 C, combined with overnight lows near 17 C to 20 C, are expected for the next four days.
However, humidex values during this period will reach the high 30s C to possibly the low 40s C.
Environment Canada said little relief is expected at night during this heat wave, and there is potential for an increase in heat-related illnesses.
The risks are greater for young children, pregnant women, older adults, people with chronic illnesses and people working or exercising outdoors.
People are urged to drink plenty of water even before they feel thirsty and to stay in a cool place.
Check on older family, friends and neighbours and make sure they are cool and have drinking water.
Read more: Third heat wave on the way for southern B.C.
Meteorologists and climatologists with Environment Canada cannot remember a season with three heat waves, especially one where temperatures in the Interior approach 40 C.
In the early 2000s and prior, B.C. would go years with no heat waves at all. Heat warnings for the region began less than 10 years ago.
Climate change is the main concern.
B.C.’s weather is driven by the behaviour of the jet stream. Due to climate change and the warming of the Arctic, the jet stream is weakening and its behaviour is changing.
A healthy jet stream would behave almost like a snake with ridges and troughs moving across a certain area, thus bringing rain at times, and sun at times.
With climate change, the weakening jet stream is stalling or holding its shape for prolonged periods of time.
The impact on weather is prolonged periods of drought and heat, or, depending on your proximity to the jet stream, prolonged periods of cold or rain.
The BC Coroners Service recently reported that 70 per cent of sudden and unexpected deaths during the June 25-July 1 heat wave were tied to extreme temperatures.
A preliminary review found that 570 of the deaths were heat-related, the service said.