Frost Date Lookup
Enter your zip code to find your average last spring frost, first fall frost, USDA zone, and growing season length.
What Are Frost Dates?
Frost dates are the average dates of the last spring frost and first fall frost for your area. They're calculated from 30 years of weather station data collected by NOAA (the National Oceanic and Atmospheric Administration).
Your last spring frost date tells you when it's generally safe to plant frost-sensitive crops outside. Your first fall frost date tells you when the growing season is ending and tender plants need protection or harvesting.
The span between these two dates is your growing season — the number of frost-free days available for warm-season crops like tomatoes, peppers, and squash.
Why Frost Dates Matter
Almost every planting decision starts with your frost dates. When a seed packet says "start indoors 6 weeks before last frost," you need to know when your last frost is. When a guide says "plant after all danger of frost has passed," it means after your average last frost date — and ideally a week or two later to be safe.
Frost dates also determine what you can grow. If your growing season is only 90 days, you'll need to choose short-season tomato varieties. If it's 200+ days, you have the luxury of growing longer-season crops like watermelons and sweet potatoes.
Understanding Frost Date Averages
These are averages, not guarantees. In any given year, your actual last frost might come 2-3 weeks earlier or later than the average date. That's why experienced gardeners often wait a week or two past the average date before planting their most frost-sensitive crops.
Microclimates matter too. If you garden in a low-lying area where cold air pools, your frost dates may be later in spring and earlier in fall than the zone average. Urban gardens surrounded by buildings and pavement (the "urban heat island" effect) may have slightly earlier springs and later falls.
What Is a USDA Hardiness Zone?
USDA hardiness zones divide the United States into regions based on average annual extreme minimum winter temperatures. Zone 1 is the coldest (parts of Alaska, with lows below -60°F) and Zone 13 is the warmest (parts of Hawaii and Puerto Rico).
Each zone is further divided into "a" (colder half) and "b" (warmer half) subzones, representing a 5°F difference. Your zone determines which perennial plants can survive your winters and serves as the foundation for planting date calculations.
To find your zone, just enter your zip code above — it's included in the results.
Frequently Asked Questions
Yes — for cold-tolerant crops. Peas, lettuce, spinach, kale, and other cool-season vegetables can be planted 2-6 weeks before your last frost date. They can handle light frosts and actually prefer cool growing conditions. Frost-sensitive crops like tomatoes, peppers, and squash should wait until after your last frost — and ideally a couple of weeks beyond it for safety.
They're based on NOAA's 30-year Climate Normals, which is the gold standard for frost date information in the U.S. However, they represent a 50% probability — meaning in any given year, there's about a 50% chance the last frost has already occurred by the average date. For higher confidence, wait 1-2 weeks past the average date.
A frost occurs when temperatures drop to 32-36°F, forming ice crystals on plant surfaces. A hard freeze occurs below 28°F and can kill many plants outright. Our frost dates refer to light frost (32°F). If you're growing particularly frost-sensitive plants, you may want to add an extra margin of safety and consider the hard freeze date, which is typically a few weeks earlier in spring and later in fall.
Last reviewed: March 29, 2026
Frost Dates by City
Browse frost dates for major US cities, or enter your zip code above for your exact location.