Photo: Flavinista · CC BY-SA 4.0Ann Arbor is drier than 81% of U.S. towns: 33 inches of precipitation a year
The coldest hours of a January night bottom out at 16° on average. May is the wettest month, February the driest. Winter nights are cold: in January they are colder than in 80% of U.S. towns. For walks and days out, the stretch from May to September brings highs of 70–83°.
A year in Ann Arbor at a glance
Each month’s typical high and low, and what it brings.
What stands out about Ann Arbor’s climate
Compared with towns across the U.S., with Ann Arbor’s place in Michigan beside it.
What a year in Ann Arbor feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 160 frost-free days a year
In half of years the last 32° night comes by May 3 and the first by October 13. Frost and day counts come from NOAA’s station at Ann Arbor U Of Mich, MI, 4 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Ann Arbor’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −7°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 61 inches of snow a winter
Snow, measured at Ann Arbor U Of Mich, MI, falls mostly in January. Precipitation (rain plus melted snow) adds up to 33 inches a year; May is the wettest month and February the driest. Rain or snow falls on about 166 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Ann Arbor
91% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Ann Arbor U Of Mich, MI.
Living with Ann Arbor’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
160 frost-free days in zone 6a. The last frost comes by May 3 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 13.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 93 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Ann Arbor from natural hazards, river flooding is the largest share (45%); heat waves, cold waves, winter storms and ice storms together are 19%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Ann Arbor and its neighbors
Every town next door is within a degree of Ann Arbor in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Ann Arbor’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Ann Arbor, MI | 16° | 83° | 33" | 61" |
| Ithaca, NY | 17° | 83° | 36" | 63" |
| Mequon, WI | 14° | 82° | 34" | 54" |
| Michigan City, IN | 19° | 82° | 39" | 65" |
| Antioch, IL | 15° | 83° | 36" | 43" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Ann Arbor averaged 1.6° warmer than the 1900s. The biggest change is in December (+2.8°).
A bigger shift than in 67% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods. In a city of 122,000 people, part of the change is the city itself: pavement and buildings hold heat (the urban heat island).
How Ann Arbor compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Ann Arbor’s place among Michigan’s.
Ann Arbor weather by month
Highs, lows and precipitation from NOAA’s grid at Ann Arbor’s center; snow, wet days and snow on the ground from Ann Arbor U Of Mich, MI. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 31° | 16° | 2.1" | 18.3" | 18 | 21 | 15° – 34° |
| February | 34° | 18° | 1.8" | 15.3" | 14 | 17 | 12° – 36° |
| March | 45° | 26° | 2.3" | 8.3" | 14 | 7 | 27° – 49° |
| April | 58° | 36° | 3.2" | 2.6" | 14 | 1 | 41° – 53° |
| May | 70° | 47° | 3.7" | 0.0" | 15 | 0 | 50° – 64° |
| June | 79° | 56° | 3.5" | 0.0" | 12 | 0 | 63° – 72° |
| July | 83° | 60° | 3.2" | 0.0" | 12 | 0 | 66° – 77° |
| August | 81° | 59° | 3.2" | 0.0" | 11 | 0 | 65° – 75° |
| September | 74° | 51° | 3.0" | 0.0" | 11 | 0 | 57° – 67° |
| October | 62° | 40° | 2.8" | 0.1" | 13 | 0 | 47° – 57° |
| November | 48° | 30° | 2.5" | 4.1" | 14 | 2 | 32° – 46° |
| December | 36° | 22° | 2.0" | 12.7" | 17 | 12 | 17° – 39° |
| Year | 58° | 38° | 33.2" | 61.4" | 166 | 59 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 12° to 36°. June is the most reliable, staying within 9°.
Where Ann Arbor’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Ann Arbor’s center.
- Snow: Ann Arbor U Of Mich, MI.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Ann Arbor U Of Mich, MI, 4 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Ann Arbor’s climate
What is the weather like in Ann Arbor?
A typical July afternoon reaches 83°, a January night drops to 16°, and about 61 inches of snow falls in a normal winter. Colder January nights than 80% of U.S. towns; cooler July afternoons than 71% of U.S. towns.
How cold does it get in Ann Arbor in winter?
January nights average 16°. About 130 nights a year reach 32° or below and 4 reach 0° or below. In the coldest January of the last 30 years the month averaged 15°.
How much snow does Ann Arbor get?
About 61 inches in a normal winter at Ann Arbor U Of Mich, MI, most of it in January, with snow on the ground about 59 days a year.
How hot does it get in Ann Arbor?
July, with a typical high of 83° and a low of 60°. About 12 days a year reach 90° (Ann Arbor U Of Mich, MI).
When is the first and last frost in Ann Arbor?
In half of years the last spring frost (32°) comes by May 3 and the first fall frost by October 13, about 160 frost-free days, at Ann Arbor U Of Mich, MI.
What growing zone is Ann Arbor in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −7°.
What is the best time of year to visit Ann Arbor?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Ann Arbor getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 67% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Ann Arbor.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.