A meteorologist with Environment Canada is warning incoming hot weather will spike highs up to 18 degrees Celsius above seasonal averages across much of British Columbia.
In many places across the province, daytime highs are expected to climb into the 30s. That could put some vulnerable people at risk, though cooler nighttime temperatures are expected to temper chances of heat illness.
“A lot of widespread daily temperature maximum records are going to break through this event. There's no doubt about that,” Armel Castellan, a warning preparedness meteorologist with Environment Canada, told reporters Thursday.
Castellan says the hot weather could exacerbate wildfires already hitting Alberta and parts of northeastern B.C. Elevated temperatures are also expected to drive further melting of the spring snow pack and could increase flood risk in some areas.
By Thursday morning, the BC River Forecast Centre maintained a flood warning for the Cache Creek area. Flood warnings indicate river levels have or will spill their banks, flooding neighbouring areas. Flood watches, which means rivers may flood, are in place for Quesnel and the Salmon River at Falkland. High streamflow advisories, meanwhile, continue to cover vast areas of B.C.’s north and Interior.
Castellan said that while it’s going to be “very warm,” nighttime temperatures will return to the teens, allowing people to cool down after a hot day.
“It's a very strong signal. It just has no potential to reach the same extremes as we saw in June 2021,” he said, referring to the deadly North American heat wave.
How to prepare for this weekend's heat
Just because this weekend won’t reach temperatures felt during the 'Heat Dome' of 2021, does not mean people shouldn’t be taking it seriously, according to Sarah Henderson, scientific director of Environmental Health Services at the B.C. Centre for Disease Control.
People most vulnerable to heat include those over 60, who live alone, with a mental illness like schizophrenia, with preexisting health conditions, disabilities, with substance use disorders, as well as anyone who doesn’t have adequate housing. Young children, as well as people who are pregnant or who work in a hot place are also particularly susceptible to heat.
Henderson recommends keeping an eye on indoor temperatures this weekend, either by looking at the thermostat or an indoor thermometer. She says if you know a person who is vulnerable to extreme heat, check in on them at least a couple of times a day, especially in the evening as temperatures remain elevated indoors.
Some symptoms of heat illness to look out for include headaches, dizziness, heavy sweating, muscle cramps, and extreme thirst or dark urine. The onset of heat exhaustion may make you feel disorientated or confused, and even escalate to an altered state of consciousness, Henderson said.
“All of those things indicate that immediate cooling is necessary and medical attention is likely required,” she said.
Anyone who starts feeling too warm should immediately take action to cool down. That could mean finding a cooler room, spraying yourself with a water bottle or putting on a damp T-shirt. Other options include sitting with your feet in water, or taking a cold shower — anything to draw the heat out of the body.
“It is critically important for people who are susceptible to this need to stay hydrated,” added Henderson. “Even if you’re not thirsty.”
If you find yourself outside, she recommends wearing light-coloured clothing, finding shade and not exerting yourself, especially during the hottest hours of the day.
“I know lots of people are going to go out and enjoy the warm weather, beautiful beaches, and that's great too, but just be aware and listen to your body,” Henderson said.
How does the new B.C. extreme heat alert system work?
Rolled out last year, the BC Heat Alert and Response System (HARS) is now integrated with Environment Canada’s three-tiered extreme weather alert system.
During the first hot weather of the season, the national weather agency may issue a special weather statement as was done Wednesday. The statement is meant to alert people to early season high temperatures, which can shock the human body in ways not seen later in the summer when people have had time to acclimatize.
If temperatures continue to go up, Environment and Climate Change Canada may issue a heat warning. This stage is rolled out when daytime highs and overnight lows hit regional thresholds for at least two days.
Across B.C., the regional temperature thresholds are:
- Lower Mainland, Vancouver Island: daytime high of 29 C, nighttime low of 16 C
- Fraser Valley: daytime high of 33 C, nighttime low of 17 C
- Southeast (including the southern Okanagan): daytime high of 35 C, nighttime low of 18 C
- Northeast: daytime high of 29 C, nighttime low of 14 C
- Northwest: daytime high of 28 C, nighttime low of 13
Issued during “very hot weather,” heat warnings may occur three times every summer, and are expected to lead to small increases in emergency room visits, hospitalizations and excess deaths. This stage triggers a B.C. HARS heat warning response but may be confined to relatively small geographic areas of B.C.
Once those temperature thresholds are met and are expected to significantly increase every day for at least three days straight, an extreme heat emergency may be issued. The third tier response — equivalent to the 2021 heat wave — could lead officials to broadcast a warning through the national text alert readiness system, radio and television.
Such conditions are expected to hit a large part of the province and lead to large increases in emergency room visits, hospitalizations and deaths.
Current modelling suggests they will occur one to two times per decade, though those estimates are expected to climb past 2050 as human-caused climate change makes extreme weather more common and more intense.
A chance to plan for the next big heat wave
Henderson said the incoming hot weather is the perfect moment for individuals and families across the province to think about what they would do differently if an extreme event like 2021 were to return.
Preparing your home for extreme heat might mean buying an air conditioning unit or heat pump for your home, or installing sun-blocking awnings or shaded films that you can stick on your windows.
At an institutional level, Henderson said, the public warning and response systems have made good progress since the 2021 North American heat wave that killed roughly 740 British Columbians.
“We are in a much better place than we were in the summer of 2021,” she said. “Are we exactly where I would like us to be and where others in the province would like us to be? No, but we are pushing quickly in that direction.”
Long-term, Henderson said there are a number of big infrastructure problems — both natural and human made — that need to be tackled to protect people from the rising threat of extreme heat.
“We can't just look at air conditioning as a solution. We need to be thinking about how we're building buildings, how we have the surrounding built environment, the available green space, the available protection from the tree canopy, and mechanical cooling when necessary,” she said.