timing
Last frost date
Last reviewed 2026-10-04
A last frost date is a probability-based estimate of when a location is likely to experience its final spring freeze. The date depends on the temperature threshold, the probability selected, and the climate record used. It is a planning reference, not a promise that frost cannot occur afterward.
What it means
Different sources may publish a 10 percent, 50 percent, or 90 percent chance that a freeze has already occurred by a date. A conservative gardener may choose a later probability for tender crops, while a frost-tolerant crop can be planted earlier with protection. Always check what temperature threshold and probability a source uses.
How it affects the garden
Warm-season crops such as tomatoes and peppers are usually transplanted after the local risk of frost has fallen and soil temperatures are suitable. Cool-season crops may be planted earlier. Floating row cover, a cold frame, or another protection method can change what is practical, but protection must be installed before the cold arrives.
The frost date finder and planting calendar can turn a location estimate into crop windows. They cannot predict a specific night's weather. Check a current forecast when planting near the edge of a window.
Example
If a location's 50 percent last spring freeze date is April 10, that means the date represents a middle probability in the chosen climate record. It does not mean every year has its last frost on April 10.
Common confusion
Last frost date is not the same as hardiness zone. A zone describes average annual extreme minimum temperature, while a frost date describes seasonal timing and probability.
Sources
NOAA U.S. Climate Normals provides the climate records used to describe seasonal freeze probabilities.
