September is over and October is here, so let’s take a look at the numbers for DLS.

The averaged high temperature was 78.2 degrees F and the averaged low, 49.6. That makes for a mean temperature of 63.9 degrees, which is 2.2 degrees cooler than the 30-year average. Believe it or not, this was the coolest September in The Dalles since 1986. I was four years old at the time. We had a string of very chilly Septembers back in the 1980s, and then none at all in the 1990s or 2000s (unless you call 2005 chilly; it was 64.2 degrees F).

That said, it wasn’t cool enough this September to really “stand out” from past years. We had cooler daytime high temps in 2004 and 2007, while 2008 had more sub-50 nights than 2018. Still, it’s pretty obvious that September earned its status as an autumn month this year. We had only a couple days in the low 90s toward the start of the month, and mild to cool almost the entire rest of the time.

October is also getting off to a cool start. Wednesday in The Dalles the high was only 65 degrees despite mostly sunny skies and a light east wind. Even in early October that’s still about 8 degrees cooler than normal. Several hundred miles to our northeast, cities like Calgary are getting record October snowfall. A deep and chilly Canadian trough has carved itself out across much of the interior West, Rockies, and Northern Plains. This is precisely the kind of upper-level setup where, if it happens in winter, can cause arctic air to spill into the Columbia Basin & Gorge. But in early October, we just get cool temps and dry air.

Today we have an interesting setup that also reminds me of winter: a moderately strong low-pressure center in the northern Pacific will slide from northwest-to-southeast, with the center passing roughly through Tillamook and then Eugene. In the wintertime there would probably be enough cold air on the northern and eastern flanks, to give Portland and/or the Willamette Valley a good snowstorm – not unlike what happened back in late February.

Of course on October 5th it’s not nearly cold enough for that, but nonetheless it is an excellent trajectory for unusually cool daytime temps today. The official forecast high for The Dalles is only 54; I think that could be a cold-high record if it actually happens. Rain and dark clouds will keep out the sun all day tomorrow, preventing much if any normal diurnal warming.

A few days ago, weather models were showing some “interesting” weather beginning early next week. An early-season arctic high pressure was supposed to slide down into Montana & Wyoming, and bring rather strong cold/dry NE wind down into eastern Washington and Oregon:

But now the models are doing what they love to do with these arctic setups: push the cold air further east. We are still slated to get some cool Canadian influence early next week, just not anything extraordinary, and it will come a couple days later:

Too bad…an easterly cold snap in the 2nd week of October would have been a fun pattern. In fact, we actually had it happen nine years ago, at almost the exact same time of the month. From the 10th through the 13th of October 2009, a modified arctic airmass spilled into the Columbia Basin from the north and east, giving The Dalles four days’ high temps 57-54-51-43 (!!!) at a time of year when the normal high is still about 67-69.

I was still living in Eugene at the time, but supposedly on the morning of the 13th there was actually a rain/snow mix in The Dalles, with minor accumulations on the hills above 1,000 feet! I don’t know of any other time in our modern weather history, when we’ve flirted with Gorge snow that early in the season. The earliest true snowfall I can recall growing up, was on October 29, 1991 – a full 2″ accumulation in the afternoon as I was going home from school. Talk about a Halloween spook!