What Is a Last Frost Date?
A last frost date is the average date of the last 32 °F night in spring. At the average date there is still a 50% chance of a later frost, which is why gardeners plant tender crops a week or two after it.
The first frost date is the fall equivalent: the average date of the first 32 °F night after summer. The days between the two form the frost-free growing season, which ranges from under 100 days in the northern Rockies to year-round in southern Florida and coastal California. Denver averages a last frost on April 30 and a first frost on October 12, a 165-day season, while Chicago's lakefront averages April 10 and November 5. The calculator is part of PlantoScan's free garden planning tools.
How Are Frost Dates Calculated?
NOAA calculates frost dates from 30 years of daily minimum temperatures at each weather station. The 1991–2020 normals give the dates with a 10%, 50% and 90% chance of a 32 °F night occurring later in spring or earlier in fall.
This calculator matches a ZIP code to the nearest of about 7,000 NOAA stations with frost records, within 50 miles, and shows the station name, distance and elevation with every result. The “average” date is the 50% value. The “safer planting date” is the 10% value: in 9 springs out of 10, the last frost has already passed by then. Stations where fewer than half of all winters reach 32 °F are labelled as rare-frost locations, and stations with no 32 °F nights at all are labelled frost-free.
What Is the Difference Between Frost and a Freeze?
Frost is ice that forms on plants and surfaces, while a freeze is air temperature dropping to 32 °F or below. A light freeze (29–32 °F) kills tender plants, and a hard freeze (28 °F and below) damages most vegetables.
Frost can form when official air temperatures read 33 to 36 °F, because plant leaves and the ground radiate heat on clear, calm nights and cool below the air around them. Cloud cover and wind reduce the risk. Frost dates in this calculator use the 32 °F threshold, the standard used for gardening frost dates.
When Should You Plant Vegetables After the Last Frost?
Hardy vegetables like peas and spinach go outdoors 3 to 6 weeks before the last frost, half-hardy crops like potatoes and carrots 2 to 4 weeks before, and tender crops like tomatoes, peppers and beans 1 to 3 weeks after.
Tomatoes need nights above about 50 °F to grow well, so they go out 1 to 2 weeks after the last frost — the tomato plant care guide covers their light, watering and temperature needs once planted. Peppers are even more cold-sensitive and stall in cool soil, so they wait 2 to 3 weeks after the last frost; the pepper plant care guide lists their ideal temperature range. Enter your ZIP code above to turn these windows into calendar dates.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | 4–6 weeks before last frost (direct sow) | hardy |
| Spinach | — | 3–6 weeks before last frost (direct sow) | hardy |
| Radishes | — | 3–5 weeks before last frost (direct sow) | hardy |
| Onions (sets) | — | 2–4 weeks before last frost (plant) | hardy |
| Potatoes | — | 2–4 weeks before last frost (plant) | half-hardy |
| Broccoli & cabbage | 6–8 weeks before last frost | 2–4 weeks before last frost (transplant) | hardy |
| Lettuce | 4–6 weeks before last frost | 2–4 weeks before last frost (transplant) | hardy |
| Beets | — | 2–4 weeks before last frost (direct sow) | half-hardy |
| Carrots | — | 2–3 weeks before last frost (direct sow) | half-hardy |
| Tomatoes | 6–8 weeks before last frost | 1–2 weeks after last frost (transplant) | tender |
| Basil | 6–8 weeks before last frost | 1–3 weeks after last frost (transplant) | tender |
| Peppers | 8–10 weeks before last frost | 2–3 weeks after last frost (transplant) | tender |
| Eggplant | 8–10 weeks before last frost | 2–3 weeks after last frost (transplant) | tender |
| Green beans | — | 1–3 weeks after last frost (direct sow) | tender |
| Sweet corn | — | 1–3 weeks after last frost (direct sow) | tender |
| Cucumbers | 3–4 weeks before last frost | 1–3 weeks after last frost (transplant) | tender |
| Squash & zucchini | 3–4 weeks before last frost | 1–3 weeks after last frost (transplant) | tender |
| Watermelon | 3–4 weeks before last frost | 2–3 weeks after last frost (transplant) | tender |
General rules of thumb; wait for soil to reach about 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season?
The growing season is the number of days between the average last spring frost and the average first fall frost. NOAA normals put it at about 165 days in Denver, 208 days on Chicago's lakefront and 236 days in New York City.
Season length decides which varieties ripen. Seed packets list “days to maturity”, counted from transplanting or sowing; a 90-day tomato fits easily into a 200-day season but needs an early start indoors where the season is short. Planning bed layouts ahead of time pays off in short seasons — a plant spacing calculator for vegetable beds shows how many transplants to start for the space you have.
Are Frost Dates the Same as Hardiness Zones?
Frost dates and hardiness zones measure different things. Frost dates mark when the growing season starts and ends, while a hardiness zone describes the coldest winter night and decides which perennials survive winter outdoors.
Two towns in the same zone can have last frost dates weeks apart, so gardeners use both: frost dates for timing annual vegetables and flowers, and the USDA hardiness zone for your ZIP code for choosing trees, shrubs and perennials.
When Is the Last Frost in Each State?
Statewide median last frost dates run from January 29 in Florida to May 22 in Wyoming, and most states span several weeks between their warmest and coldest areas. Each state page lists frost dates and tomato planting dates by city.
- Alabamamedian Mar 21
- Alaskamedian May 18
- Arizonamedian Feb 18
- Arkansasmedian Mar 28
- Californiamedian Feb 6
- Coloradomedian May 9
- Connecticutmedian Apr 20
- Delawaremedian Apr 7
- Washington, D.C.median Mar 24
- Floridamedian Jan 29
- Georgiamedian Mar 23
- Idahomedian May 15
- Illinoismedian Apr 17
- Indianamedian Apr 22
- Iowamedian Apr 28
- Kansasmedian Apr 16
- Kentuckymedian Apr 16
- Louisianamedian Feb 28
- Mainemedian May 6
- Marylandmedian Apr 5
- Massachusettsmedian Apr 27
- Michiganmedian May 3
- Minnesotamedian May 4
- Mississippimedian Mar 16
- Missourimedian Apr 11
- Montanamedian May 20
- Nebraskamedian Apr 27
- Nevadamedian Apr 20
- New Hampshiremedian May 7
- New Jerseymedian Apr 15
- New Mexicomedian May 2
- New Yorkmedian May 2
- North Carolinamedian Mar 31
- North Dakotamedian May 12
- Ohiomedian Apr 24
- Oklahomamedian Apr 4
- Oregonmedian Apr 14
- Pennsylvaniamedian Apr 27
- Rhode Islandmedian Apr 22
- South Carolinamedian Mar 24
- South Dakotamedian May 6
- Tennesseemedian Apr 6
- Texasmedian Mar 10
- Utahmedian May 6
- Vermontmedian May 13
- Virginiamedian Apr 11
- Washingtonmedian Apr 15
- West Virginiamedian Apr 23
- Wisconsinmedian May 4
- Wyomingmedian May 22
Median last frost across each state's ZIP codes, NOAA 1991–2020 normals.
Frequently Asked Questions
- What is the last frost date for 2026 or 2027?
- Average frost dates come from 30 years of records, so the same date applies every year. The actual last frost in any spring can arrive two or three weeks earlier or later, so check the 10-day forecast before planting tender crops.
- Can I plant before the last frost date?
- Hardy crops such as peas, spinach, radishes, onions and broccoli tolerate light frost and go in 2 to 6 weeks before the last frost. Tender crops such as tomatoes, peppers, beans and squash wait until 1 to 3 weeks after it.
- How do I protect plants from a late frost?
- Cover plants overnight with frost cloth, old sheets or buckets, removing plastic covers by morning, and water the soil the day before, since moist soil releases more heat than dry soil. Bring seedlings in containers indoors.
- Why is my frost date different from my neighbor's?
- Frost dates shift with elevation, slope and nearby water. Cold air drains into valleys, cities stay warmer than open farmland, and a garden a few hundred feet higher can see frost a week later in spring.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code locations: U.S. Census Bureau 2023 ZCTA Gazetteer. Each ZIP code uses the nearest station with frost records; conditions at your garden can differ.