As La Niña is expected to bring a colder, wetter winter to Portland, we're only a few weeks out until our first freeze, too.
The big picture: The first freezing temperatures after summer are coming later on the calendar than they used to, according to a new analysis.
For example, compared to 1970, Portland's first freeze now arrives 12 days later per Climate Central, a climate research group — in line with the national average.
Between 1991 and 2020, the average first freeze date in Portland was Nov. 16.
Caveat: The group defines "first freeze" as the first calendar date from Aug. 1 onwards with low temperatures at or below 32°F.
"First freeze" is different from "first frost," which can happen with slightly higher temperatures — and damage frost-intolerant crops.
The bottom line: Warmer fall temperatures could disrupt "important ecological cues in forests, farm, and gardens," according to Climate Central, extending allergy season and hurting summer crop yields.