Probabilities, not guarantees. Frost dates are 30-year statistics (1991–2020) from the nearest NOAA weather station, not a forecast. Local spots such as low ground, valleys and open fields can freeze earlier and later. Check your local National Weather Service forecast before planting.
Freeze data: NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020 (public domain). ZIP locations: U.S. Census Bureau ZCTA Gazetteer (public domain). Hardiness zones: 2023 USDA Plant Hardiness Zone Map ZIP listing, PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed Oct 17, 2026; this site shows the zone as text and is not the official USDA map. Not affiliated with or endorsed by NOAA, USDA or Oregon State University.
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