Warm, dry start to fall on B.C.’s South Coast raises concerns for wetter days ahead

Today marks the first full day of fall, but don’t pack away your summer clothes just yet.

The first full day of fall is here, but so far the season hasn’t looked much like it on B.C.’s South Coast.

September has been marked by warmer-than-usual days and below-average rainfall, according to Environment and Climate Change Canada.

Warmer and drier than normal

“It’s been a decent start to the fall,” said Matt Loney, a meteorologist with Environment Canada. “Meteorological fall starts on Sept. 1, and so much of September has been warmer and drier than normal.”

He noted that inland areas have seen the most dramatic temperature differences. “We still have these temperature contrasts between coast and inland. So we typically see the inland sections between five and seven degrees higher, as we’ve seen for much of September. So it has been running above normal for much of the month so far.”

On the rainfall side, it’s also been quieter than usual.

“We’re slightly drier than normal,” Loney said. “We did have a few rain showers there last week… September is typically still somewhat of a dry month. We’re not quite into the rainy season yet. October really changes things.”

Drought and fire risk

That dry trend, paired with hot weather through late summer, has heightened concerns about drought and extended the wildfire season.

“We’ve seen precipitation deficit building for quite a significant portion of the province,” Loney said.

“The drought numbers would suggest that these are having an impact around the province,” he continued.

“The later part of July into August was quite dry and hot for much of the province. So those deficits built in the latter part of the summer and continue, as we speak.”

While northern parts of B.C. are seeing more rain this week, Loney noted the southern half of the province will be slower to catch up.

Flooding concerns if heavy rain returns quickly

With ground conditions already so dry, officials are watching closely for what happens when wet weather eventually returns. “If it comes all at once too quickly, yes, that can have an effect,” Loney explained.

“It can exacerbate flooding, if it comes too quickly. So we’re in constant collaboration with [the River Forecast Centre]. They end up releasing, of course, the flood-stage watches for rivers.”

What’s ahead: La Niña and a marine heat wave

Looking further into the season, Loney said a “mild La Niña” is in the forecast — though its effects will likely be felt later in fall and into the winter months.

“The big thing that we’re watching is this, what we call marine heat wave,” he added. “In the North Pacific, temperatures there are quite high, above normal and the sea surface temperature, so that can have an effect on the amount of precipitation and warmth we might see on the west coast.”

That trend could bring more moisture than normal. “Our seasonal forecast, for example, showed higher probability of warmer than normal temperatures, and for… more precipitation, higher probabilities of precipitation for much of the southern portion of the province.”

‘Raincouver’ living up to its name?

When asked if Vancouver could live up to its nickname this year, Loney said: “It’s quite possible. I don’t think we’ll see a higher-than-normal count of say, atmospheric rivers… But we might see that precipitation is partitioned in such a way that we get… slightly more rain with each passing atmospheric river. So that would tend to pump up those precipitation numbers a bit.”