Detroit, MI Frost Dates: Last Spring and First Fall Frost

Frost leaves Detroit on April 27 and comes back on October 25 when the odds are even, a window of 181 days for tender plants.

Dates at even odds leave half of all years unprotected. The safer pair for Detroit is May 11 in spring, which only one year in ten passes, and October 10 in fall, which one year in ten arrives before. Against the 100-city median of 229 days, Detroit has 48 days less room before frost returns.

NOAA measured them at Dearborn #2 (station USC00202016), about 4.4 miles south-west of the Census Bureau's internal point for Detroit and about 600 feet above sea level.

Last spring frost in Detroit

Frost is still possible on April 12 in nine springs out of ten and on April 27 in five; only one spring in ten sees a freeze as late as May 11.

Only 29 days separate the earliest and latest of these dates, a tighter run than most of the 100 cities here, so the typical date is a fairly dependable guide in Detroit.

When is the first frost in Detroit?

A first freeze on or before October 10 happens one fall in ten. By October 25 half of years have had one, and by November 7 nine years in ten have.

The early and late fall dates are only 28 days apart, a narrow band next to most cities here, so the first freeze keeps close to its schedule in Detroit.

The growing season in Detroit

That is shorter than most places on these pages, so days to maturity on the seed packet matter more than usual. Plan on 159 days in a short year, 181 days in a typical one, and as many as 199 days in a long one.

The season lengths come from NOAA's simulated years, not from subtracting one typical date from the other, so the two will not match to the day. Every winter in the record reached freezing at Dearborn #2, so the dates above describe a real yearly event, not a rare one.

28°F dates in Detroit

NOAA's even-odds hard freeze dates for Detroit are November 6 in fall and April 15 in spring, 12 days and 12 days from the matching 32°F dates. One spring in ten still has a 28°F night on or after April 30, and one fall in ten sees the first by October 24.

What this means for planting in Detroit

The University of New Hampshire Extension sheet times each crop from the last frost. For Detroit's typical date, April 27, that means cabbage on March 30, lettuce from March 30 to April 6, seed potatoes from April 13 to April 20, and, once the frost is behind you, peppers on May 11 and beans on or after April 27. The University of New Hampshire Extension sheet gives peas no frost count at all; sow them as soon as the soil thaws.

The late date comes 14 days after the typical one; choose it for plants you cannot cover.

Detroit's first frost leaves room for only 28 of the 34 fall crops, counting back NC State Extension's days to harvest and University of Georgia Extension's harvest allowance of 18 days; for the other 6 the last planting day falls before July. The slowest crop that still fits is broccoli, at 98 days, and it has to be planted by July 4 to beat the early date.

Worked example: a tomato plan for Detroit

Suppose you want tomatoes in Detroit. University of New Hampshire Extension says to set transplants out one to two weeks after the last frost. Counting from the typical date, April 27, the window runs from May 4 to May 11. Counting from the late date, May 11, it moves to May 18 through May 25, which is 14 days later.

Indoors, tomato seeds go in six to eight weeks ahead of set-out; from the first day of the late window that is March 23 to April 6.

That leaves 138 days against 75 to 85 days for the plants to reach harvest, so even the late schedule fits in an early-frost year with 53 days to spare.

Where Detroit's numbers are measured

The nearest usable station stands 4.4 miles south-west of Detroit's internal point, near the city but not in it.

NOAA lists it at about 600 feet, higher than 44 and lower than 55 of the 100 stations in this set. In NOAA's file the record is marked R, meaning representative.

No elevation is available for Detroit in the Census data we saved, so the station's height may or may not match your garden's. Compare nearby stations in the frost dates tool if it does not, and err toward the colder dates.

Nearby cities and their frost dates

Here is how Detroit, with a last frost on April 27 and a first frost on October 25, compares with the three nearest cities on these pages, the closest being Toledo, OH at 55 miles.

• Toledo, OH, 55 miles to the south-west: last frost April 20, first frost October 27, 188 days frost-free; spring frost ends 7 days sooner than in Detroit, and the season is within about a week of Detroit's.
• Cleveland, OH (96 miles, south-east): spring frost ends 19 days sooner than in Detroit, and it has 36 days more without frost. Its typical dates are April 8 and November 12, with 217 days frost-free.
• Fort Wayne, IN, 138 miles to the south-west: last frost April 24, first frost October 21, 178 days frost-free; its last frost is nearly the same as Detroit's, and the season is about the same length as Detroit's.

Put the frost dates to work

To go beyond the crops above, use the spring planting planner and fall planting planner, both set to this station. The frost dates tool shows the full odds for Detroit, and the hardiness zone lookup gives the winter-cold zone for your ZIP code.

Looking for another city? The city frost dates index lists every page, grouped by state.

Where these numbers come from

NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11) supply every frost date here, unchanged from the station's record, and NOAA's documentation defines the probabilities. The city and its internal point come from the Census Bureau's 2024 Gazetteer of places, and the ranking by size from the Census Bureau's Vintage 2024 city and town population estimates, which put Detroit at 645,705 people.

The planting dates apply the count rules in University of New Hampshire Extension, NC State Extension and University of Georgia Extension to this station's dates, with nothing added. Our methodology describes the tests behind every number.

NOAA's dates say how often frost has come, not when it will. Check the forecast before planting and keep a cover on hand.