How did the Jasper wildfire get so out of control?

The fire that ripped through Jasper came in fast and ferocious. Events moved quickly — there was a surprise evacuation of 25,000 people late Monday night and less than 48 hours later, a wildfire south of Jasper breached the townsite. 

Now, many people are asking: How did it get so out of control?  

The answer isn't simple. Experts say the flames of this monster fire were fanned by a combination of extreme heat, drought, and an abundance of flammable materials. 

In the weeks leading up to the wildfire, Jasper was in the midst of a heat wave, with most days soaring into the 30s. On Sunday, July 21 — the day before the evacuation — it reached 38 C. 

It has also been particularly dry.

In the first three weeks of July, less than one millimetre of rain had fallen in Jasper, according to Environment Canada statistics. Normal precipitation for the month is about 52 millimetres, based on data from 1991 to 2020.

Those types of hot and dry conditions will increasingly become more common in Alberta, said Mike Flannigan, professor of wildland fires at Thompson River University in Kamloops, B.C.  

"Future modelling suggests during our fire season in Canada at least, we're going to be actually drier than historic norms … there's no rain to help us out of this situation, bottom line," said Flannigan. 

Jet streams — air currents that flow from east to west across the globe — play a major role in the weather conditions Alberta experiences. When the jet stream kinks, it creates ridges where air sinks and towns or cities within a ridge will experience warm and dry conditions. 

"That's what brought the heat dome in 2021, and brought [the] extended, hot dry period in 2023," said Flannigan. 

"Eventually that ridge breaks down or moves off and it's often associated with a cold front. And cold fronts are notoriously extreme situations for fire."  

These were the conditions Jasper experienced in the weeks leading up to the wildfire. The cold front brought wind and lightning, which combined with the heat to create a perfect storm for fire.

Officials believe the fire that breached Jasper from the south side of town was likely caused by lightning. 

As the fire grew and travelled north, Flannigan believes it picked up energy to form a pyrocumulonimbus cloud — a thunderstorm cloud that can create its own weather.