Frost Date Calculator by ZIP Code

Frost Dates & Grow Zone

Enter your ZIP code or Canadian postal code for sub-region accurate frost dates and your hardiness zone.

Country

🍁 Canadian zones use additional factors beyond minimum temperature (snow cover, wind, frost-free days). Results use Canadian Plant Hardiness Zones. Verify at planthardiness.gc.ca.

Your ZIP Code

5-digit US ZIP code

⚙️ Adjust for microclimate / elevation

Override any value after looking up your code — useful for hilltops, valleys, urban heat islands, or coastal areas.

Last Spring Frost

First Fall Frost

Zone Override

Min Temp Override

Last Spring Frost

—

average date

First Fall Frost

—

average date

Growing Season

—

frost-free days

Min Winter Temp

—

average low

🌱 Next step: Use your last frost date in the Seed Starting Calculator to build your full planting schedule.

Frequently Asked Questions

What is a frost date?

A frost date is the average date of the last spring freeze or first fall freeze in your area. Gardeners use the last spring frost date to time seed starting and transplanting, and the first fall frost date to plan harvest deadlines.

How do I find my USDA hardiness zone?

Your USDA Plant Hardiness Zone is based on the average annual minimum winter temperature in your area. Enter your ZIP code above to look up your zone automatically. This calculator now returns sub-region data rather than a state average — so a coastal Maine ZIP will return different dates than an Aroostook County ZIP.

What does 'days to last frost' mean for seed starting?

Seed starting schedules count backward from your last frost date. For example, 'start 6–8 weeks before last frost' means you count back 42–56 days from your local last frost date to find when to sow indoors.

How is the Canadian hardiness zone different from USDA?

Canadian Plant Hardiness Zones incorporate more factors than the US system — including snow cover depth, maximum summer temperatures, frost-free days, January rain, and wind speed. A Canadian zone 5 is often warmer in practice than a USDA zone 5, because Canadian zones account for snow insulation. Always verify your exact zone at planthardiness.gc.ca.

Why doesn't my exact street address matter for frost dates?

Frost dates are averages across a climate region — not a precise forecast for your property. Elevation, proximity to water, slope aspect, and urban vs. rural settings all affect your true microclimate. Use the manual override section to adjust for your specific situation.