1 of 4 stations freeze at 2 inches in a typical winter, 1 of them to 8 inches or deeper.
Station by station
Each bar runs from the typical first freeze to the typical last thaw at that depth, the median over the station's complete winters on record, with the typical number of frozen days after it. Frost reaches the deeper probes later in the winter. A depth that froze in fewer than half of its winters has no typical dates. Stations: 1 typically freeze, 3 never stayed at or below 32°F for 3 days running.
In 3 complete winters on record, 2-inch soil never stayed at or below 32°F for 3 days running.
Lowest daily reading at each depth, each from a different day: 35.8°F at 2 inches, 37.8°F at 4 inches, 38.8°F at 8 inches, 42.6°F at 20 inches and 45.1°F at 40 inches.
In 4 complete winters on record, 2-inch soil never stayed at or below 32°F for 3 days running.
Lowest daily reading at each depth, each from a different day: 34.5°F at 2 inches, 35.6°F at 4 inches, 37.8°F at 8 inches, 40.1°F at 20 inches and 44.2°F at 40 inches.
In 4 complete winters on record, 2-inch soil never stayed at or below 32°F for 3 days running.
Lowest daily reading at each depth, each from a different day: 31.3°F at 2 inches, 32.5°F at 4 inches, 31.1°F at 8 inches, 31.5°F at 20 inches and 32.5°F at 40 inches; a reading at or below 32°F lasted only a day or two.
Typically freezes to 8 inches, not to 20.
A winter runs July to June. Our station readings come from one grass-covered site per station at five fixed depths, and often show shallower frost than regional figures.
Where the ground is frozen today across the US · Oregon soil temperature · First frost and frost depth guide