How Frost Dates Are Determined
The chart below shows the average dates for the last spring frost and the first fall/winter frost dates for each USDA Hardiness Zone. These dates are typically defined by the day where there’s a 50% chance of being frost-free. If you want to ensure the safety of your plants, you may want to adjust these dates by a full two weeks (forward for spring, backward for fall/winter).
Be aware that within an individual hardiness zone, the dates for first and last frost can significantly vary. Within a single zone, the average dates can vary by as much as a week.
If you do not know your Hardiness (planting) Zone, click here, or visit these resources:
General Last and First Frost Dates, by Hardiness Zone
|USDA Zone||Last Frost Date||First Frost Date|
|1||June 1-30||July 1-31|
|2||May 16-31||Aug 1-31|
|3||May 1-15||Sep 1-30|
|4||April 16-30||Oct 1-15|
|5||April 1-15||Oct 16-31|
|6||Mar 16-30||Nov 1-15|
|7||Mar 1-15||Nov 16-30|
|8||Feb 1-28||Dec 1-15|
|9||Jan 1-30||Dec 16-31|
|10||Rare or no Freeze||Rare or no Freeze|