'139 lightning strikes': How rare was Vancouver's thunderstorm this week?

It was certainly long and striking. But how does it measure up?

Did you find Thursday's storm pretty spectacular, and spectacularly rare? Well, that's because it was. Thunderstorms are rare in Metro Vancouver, period, says Environment Canada meteorologist Jenn Cowall.

But the one that happened on July 16 wasn't your average lightning show. It's been a couple of years since we've had such a productive lightning event, she says. The department uses a lightning detector in the City of Vancouver alone that measures strikes within a 50-kilometre circumference.

Last night's thunderstorm started in Delta around 9 p.m. and moved across the region until about 10:30 p.m. But some strikes were recorded near Squamish and the Fraser Valley until 11:30 p.m. In total, the department recorded a whopping 139 lightning strikes in the 2.5-hour period, something that the region hasn't come close to experiencing this year.

In 2025, one night in August had 128 strikes, the meteorologist says. But August 2024 was a banner month in the region. One evening experienced a whipping 333 lightning strikes, more than twice of what we witnessed last night — wowsa.

Vancouver thunderstorm: Why are these weather events so rare, and what produces them? Thursday's thunderstorm was so spectacular because it lasted a long time with a high density of strikes accompanied by loud booms. It also followed a string of dry days and produced several heavy downpours.

The genesis of the weather event was a low-pressure system moving onshore from the Pacific, carrying the convective elements necessary for a thunderstorm in a place that doesn't produce enough energy from ground heating alone, Cowall says. The storm produced 18,000 lightning strikes province-wide over a 24-hour period, which sounds extraordinary, but doesn't tell the story of how it impacted specific areas. Other days this month experienced significantly more lightning strikes because of how lightning is produced in places like the Interior.

"There have actually been other days earlier this month where we've had 26,000 strikes [B.C.-wide] because [the storms are] generated by the surface. And so, those are way, way more frequent in their strikes because there's just more energy coming from the surface heating," she explains. Metro Vancouver doesn't experience thunderstorms from surface heating alone.

Instead, a trigger from a weather event is required, such as the "lift" in Thursday's low-pressure system. "When we get thunderstorms here, they're often driven by something that's triggering it offshore as opposed to being that classic, say, prairie-style thunderstorm that is driven by surface heating, just making the air convective because there's so much rising air by how hot it is," she says. What was special about it?

On average, Vancouver experiences one day a month of thunderstorms — that's it. And typically you won't see upwards of a hundred strikes. "It's more common to happen in the summer because we do sometimes have that additional surface heating.

Whereas, if this happened in the winter, it would have to be completely driven by something that was cold and convective, which is just more rare," she notes. Noteworthy thunderstorms may only happen a few times annually, and, as previously mentioned, ones of this calibre happen maybe once a year. Cowall says many factors can produce a thunderstorm, including moisture, instability, shear (a shift in atmospheric wind) and a trigger.

"If it's warm enough, a lot of those factors can be brought on just by the surface heating," she says. The Metro Vancouver weather forecast calls for calmer conditions for at least the next week.