When is the last frost in Ann Arbor, MI?

The average last spring frost (50% probability of 32°F) in Ann Arbor is around May 8, based on NOAA/NCEI 1991–2020 normals at the Ann Arbor Muni Ap, MI station (5.9 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Ann Arbor?

The average first fall frost in Ann Arbor, MI is around October 4, giving roughly a 147-day frost-free growing season.

What planting zone is Ann Arbor, MI?

Ann Arbor is in USDA plant hardiness zone 6a (average annual extreme minimum temperature -10 to -5°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Ann Arbor?

In Ann Arbor, MI the warmest month is July (avg high 84°F) and the coldest is January (avg low 16.3°F). It averages about 37.9″ of precipitation a year and 59.3″ of snow.

Home › Michigan › Ann Arbor

Ann Arbor, MI Planting Calendar & Frost Dates

USDA hardiness zone 6a · ZIP 48103 · elevation 254′ · NOAA & USDA data

Ann Arbor is in USDA hardiness zone 6a (winters can dip to -10 to -5°F), with a growing season of about 147 days between the average last spring frost (May 8) and first fall frost (October 4). The warmest month is July (avg high 84°F); the coldest is January (avg low 16.3°F). It averages 37.9″ of precipitation a year and 59.3″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp -10 to -5°F

Last spring frost

May 8

avg (50% prob, 32°F)

First fall frost

October 4

avg (50% prob, 32°F)

Growing season

147 days

frost-free window

Warmest month

July

avg high 84°F

Month-by-month typical weather in Ann Arbor

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Ann Arbor Se, MI (8 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	31.7	16.3	24	2.8	16.6
February	34.8	16.3	25.5	2.4	17.1
March	45.1	24.9	35	2.8	7.3
April	58.2	34.2	46.2	3.3	2.4
May	70.4	45.5	57.9	3.8	0
June	79.7	55.5	67.6	4.3	0
July	84	59	71.5	3.9	0
August	81.5	57.9	69.7	3.3	0
September	75.1	49.7	62.4	3	0
October	62	39	50.5	2.9	0.1
November	48	29.6	38.8	2.7	3.9
December	36.2	22.2	29.2	2.6	11.9

What to plant when in Ann Arbor

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 27 · Transplant out: May 15
Peppers	warm	Start seeds indoors: March 13 · Transplant out: May 22
Cucumbers	warm	Direct sow: May 15
Zucchini / squash	warm	Direct sow: May 15
Bush beans	warm	Direct sow: May 15
Sweet corn	warm	Direct sow: May 15
Basil	warm	Transplant out: May 15
Peas	cool	Sow (spring): April 3 · Sow (fall): August 9
Spinach	cool	Sow (spring): March 27 · Sow (fall): August 9
Lettuce	cool	Sow (spring): April 10 · Sow (fall): August 9
Kale	cool	Transplant (spring): April 17 · Sow (fall): July 26
Broccoli	cool	Transplant (spring): April 24
Carrots	cool	Sow (spring): April 17 · Sow (fall): July 26
Onions	cool	Transplant (spring): April 10
Potatoes	cool	Plant seed potatoes: April 24
Radishes	cool	Sow (spring): April 10 · Sow (fall): August 23

Dates are computed from Ann Arbor's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Michigan

Novi, MI Westland, MI Livonia, MI Taylor, MI Dearborn Heights, MI Southfield, MI Lincoln Park, MI Dearborn, MI

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Ann Arbor Muni Ap, MI, 5.9 mi (confidence: high). Monthly weather normals: Ann Arbor Se, MI, 8 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.