Frost Date Calculator

Enter your ZIP code to find your average last spring frost and first fall frost dates — plus your full growing season window.

Find Your Frost Dates

Covers ZIP codes in all 50 U.S. states. Results are based on 30-year NOAA climate normals.

ZIP code not found. Try a nearby ZIP or check our coverage area below.

Now covering ZIP codes in all 50 U.S. states | Based on 30-year NOAA climate normals

—

Zone —

Frost-Free Growing Season

—

— days

Average Last Spring Frost

—

Safe to plant warm-season crops after this date

Average First Fall Frost

—

Bring tender plants in or cover before this date

Your Growing Season at a Glance

Frost risk

Shoulder (transition)

Frost-free growing season

Key Planting Dates Derived from Your Frost Dates

—

Start tomatoes & peppers indoors

—

Direct sow cool-season crops

—

Safe to transplant warm-season crops

—

Start fall cool-season crops

Dates are 30-year averages (NOAA normals). Actual frost dates vary year to year — always monitor local forecasts.

How It Works

Three Steps to a Better Garden

No guesswork — just enter your ZIP and get a complete planting picture.

Enter Your ZIP Code

Type your 5-digit ZIP code above. GardenCalc looks it up against 30-year NOAA climate averages for your exact location.

See Your Frost Dates

Instantly see your average last spring frost and first fall frost, your frost-free growing season length, and your USDA hardiness zone.

Plan Your Garden

Use the derived key planting dates — when to start seeds indoors, transplant, sow cool-season crops, and prep for fall.

Common Questions

Frost Date FAQ

What is the "last frost date"? ▼

The last frost date is the average calendar date after which a killing frost (28°F or below) is unlikely in spring. It's calculated from 30 years of NOAA weather station data. There's typically a 50% chance of frost on or before this date — so many gardeners wait 1–2 weeks past it before transplanting frost-sensitive plants like tomatoes.

What is the "first fall frost date"? ▼

The first fall frost date is the average date when temperatures first dip to 32°F or below in autumn. This signals the end of the warm growing season for frost-tender plants like tomatoes, basil, squash, and peppers. Plan to harvest or cover sensitive crops before this date.

Are these dates guaranteed to be accurate? ▼

No frost date is a guarantee — they are statistical averages based on historical data. In any given year, the actual frost dates may be earlier or later than the average. For important transplants, monitor local weather forecasts and be prepared to cover plants when frost is predicted. Microclimates (low-lying areas, urban heat islands, proximity to water) also affect local frost timing.

How is the growing season length calculated? ▼

The growing season is the number of days between the average last spring frost and the average first fall frost. For example, if your last frost is March 15 and your first frost is November 15, your growing season is approximately 245 days. This is the typical frost-free window in which you can grow warm-season crops outdoors without frost protection.

What does the USDA Hardiness Zone mean? ▼

The USDA Plant Hardiness Zone Map divides North America into 13 zones based on average annual minimum winter temperatures. Each zone represents a 10°F range. Zone 9a, for example, has average annual minimum temperatures between 20°F and 25°F. This zone rating is used on plant tags to indicate whether a perennial plant can survive winter in your area.

When should I start seeds indoors? ▼

Most warm-season crops (tomatoes, peppers, eggplant) should be started indoors 6–8 weeks before your last frost date. Crops like squash and cucumbers do best started 2–4 weeks before the last frost, or direct sown after it. Use the derived planting dates shown in your results as a starting point, and adjust based on the specific seed packet instructions for each variety.