I learned a new meteorological term this week: heat dome. What’s a heat dome, you ask?
A heat dome is when the summer sun warms the air, which then rushes up into the atmosphere to form a dome of slow-moving hot air. It’s different than an ordinary high-pressure system, however, because it’s stuck and can take a long time to move on.
The Pacific Northwest and British Columbia experienced a heat dome this past weekend, which has now moved on to Alberta. And so, this morning, for the first time in four days, I woke to comfortable temperatures.
Yup. It was four days of intense heat where the temperature was 20°C above the seasonal normal. Because we had a typical June-uary here in Vancouver (meaning the average daily high was about 18°C), the sudden change in temperature was a bit of a shock. But the time of year also means there is little time for the temperatures to cool down at night. It doesn’t get dark until after 10 p.m. and by 4 a.m., it is already starting to get light.
I know that many parts of the world have endured extreme heat waves before — northern Europe comes to mind — but it’s pretty unusual for Vancouver, which has a temperate climate and rarely experiences extreme hot or cold. I haven’t felt this warm in Vancouver in a very long time — more than a decade, to be honest.
Yesterday a colleague in Toronto asked me if we were also experiencing the same humidity that Toronto gets. I don’t think so, I told her. To my memory (which could certainly be faulty given the time that has passed since I lived in Toronto), what is an extreme heat wave for Vancouver actually feels much like a normal summer day for Toronto.
That’s not to say this heat dome didn’t have serious outcomes. At least 486 sudden and unexpected deaths have occurred in Metro Vancouver since Friday, which is about 300 deaths more than is typical in that time frame. To put that number into context, the health risks from this heat wave are greater than Covid right now. Much of the health risk is because the homes in Vancouver aren’t built to withstand this heat — most of us don’t have air conditioning. To provide some relief, cooling centres were set up in local community centres and libraries.
Until this past weekend, the hottest ever recorded temperature in Canada was 45°C in Saskatchewan, set back in July 1937. That record was shattered on Sunday at Lytton in the Fraser Canyon, about 250 kilometres northeast of Vancouver, when the temperature reached 46.6°C. That record lasted a mere 24 hours. And it was broken again yesterday, with a record high of 49.6°C. For my readers who think in Fahrenheit, that’s 121°F. These are not the kinds of records we want to be setting. That’s hotter than the highest-ever recorded temperature for Las Vegas.
Naturally, when there are hot, dry conditions, there is always the threat of wildfires. Tonight, Lytton burned to the ground. Residents of the village had only minutes to evacuate.
To get through my commitments for this week, I started work at 6 a.m. so I could stop at noon. And then, I headed to the beach where I found myself a comfortable spot in the shade. I do not know how I’d have gotten through these past few days without those hours of respite that the sea breeze off English Bay provided me.