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The first full day of fall was this week but the unsettled, cooler and damper weather pattern expected this autumn has already been settling in for a few weeks now.

A high pressure system parked over much of B.C. from June to mid-August, set records for high temperatures forest fires.

That has all changed over the past few weeks as cooler, damper weather has predominated in the Thompson-Okanagan a precursor to what was expected to be a stormy fall.

READ MORE: One more day of the heat wave pushes Okanagan and Canadian records even higher

“Over the past several weeks there’s been some indications that the La Nina may not be quite as strong as we thought when we made up the forecast earlier, but at this point we’re not going to change anything,” Brett Anderson, senior meteorologist with AccuWeather told iNFOnews.ca, Sept. 22.

“Basically, what we’re looking at is an increase in storminess across Western Canada, especially in British Columbia, for the fall of 2021 which should result in above normal rainfall in western portions of the province. In Central and eastern portions of the province, we’re going to have near normal rainfall for the fall.”

That means, for example, the heavy rain expected to hit Vancouver and the West Coast on Sunday and Monday will likely just bring showers to the Thompson-Okanagan.

Still, given the extent of the forest fires this summer, there is likely going to be enough rain in this region to cause some problems.

READ MORE: Kamloops Fire Centre sees record-breaking number of hectares burned this year

“The main concern with this kind of pattern is, there are a lot of burn scars out there,” Anderson said. “When you get rainfall, you know what that means, especially in hilly terrain. You can get mudslides and flash floods easily.”

READ MORE: UPDATE: Highway 1 reopens after mudslide near Spences Bridge

So, what is this La Nina thing and why does it matter to this region?

“La Nina is an abnormal cooling of the surface water along the equator in the central Pacific,” Anderson said. “That’s due to a change in wind direction. The wind shifts more to an easterly direction. That pushes the warmer surface water out to the western Pacific, leaving the central and eastern Pacific cooler than normal.

“When that happens, it tends to influence the jet stream pattern, especially later in the fall and into the winter time. What we typically see with that, but not all the time, is a stronger jet stream that tends to be directed into British Columbia, thus the stormier pattern we tend to get. Also, in winter, it tends to be colder than normal.”

Water in the Pacific Ocean, right now, is above normal temperatures so the really cold air will likely be further to the north. There’s a good chance, however, that skiers will be happy with an earlier than normal snowfall.

“Most of the chilly air is going to be hanging out in Northern B.C. and up into the Yukon Territory but, occasionally, we’ll get some cooler shots coming down,” he said.

As for winter, it’s hard to predict that far away, given the effects of climate change, Anderson said.

“There will still be winters that will be cold, but they will be further and further between,” Anderson said. “It doesn’t look quite as wet as we thought a month ago but it’s still early yet. It does not look like an overly mild winter. I would say close to normal temperatures.”

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