Warm weather might delay this year’s fall foliage

October 5, 2022 5:20 PM

Matt Gray,

Posted: October 5, 2022 5:20 PM

Updated: October 5, 2022 6:35 PM

by Matt Gray

SPOKANE, Wash. — October is when we look forward to the brilliant colors of autumn revealing themselves; from the yellow larches on the high mountainsides to the reds and oranges of maple and ash in the valleys below. It’s one of the prettiest and most photo-worthy times to live here in the Inland Northwest.

Here we are on October 5th, and most trees don’t look like they’re even close to turning for fall. Sure, you may see a tree or two in your neighborhood whose green is starting to fade, but it still looks like summer for the most part. It feels like summer outside too, and don’t for a second think that those two facts are not related.

Leaf Colors in the growing season and fall

Longer nights and colder weather trigger trees to close off the veins to each leaf and get ready to go dormant for the winter. As this happens, the leaves begin to lose their green color as food production in the leaf stops. It’s then that the other colors present in chemical compounds in the leaf are revealed.

The thing is that so far in 2022 we’ve had hardly any colder weather. September was the third-warmest on record in Spokane. So far in October high temperatures have been at 1o to 20 degrees above normal and lows have been over five degrees warmer than the average. Without chilly nights to help trigger the leaves to start shutting down, it’s likely that many trees are still operating like it’s summer. We still keep losing daylight though, which means that eventually there won’t be enough sun for the leaves to keep making food to store for winter.

hot weather dulls leaf colors, but sunny and cool weather makes them pop

So what does this mean for your leaf peeping this year? With warm and dry weather expected for most of October, we should not expect the peak of fall foliage until pretty late in the month. It’s likely it will be a short leaf season. Unless there’s some decent rainfall this month the colors could come out dull, and the continued warmth may also keep the leaves a more muted color anyway when they do finally turn. A key indicator will be when and how bright the change is up in the mountains. That will come earlier in the month than lower elevations.