Ann Arbor, Michigan climate: Normal weather by month, frost dates and records
Ann Arbor's normal year runs from 15°F January nights to 84°F July afternoons, with 29.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.8°C, January lows of −9°C, July highs of 29°C, 756 mm of precipitation a year.
- NOAA stationAnn Arbor Municipal Airport
- Station IDUSW00094889
- Location42.22°N 83.74°W
- Elevation839 ft (256 m)
- From the center4 miles
- Population122,925
On October 14, the normal high in Ann Arbor is 62°F and the normal low 39°F, and the chance of measurable rain or snow is 38%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Ann Arbor.
- Jan 32° 15°
- Feb 35° 16°
- Mar 45° 25°
- Apr 59° 35°
- May 70° 46°
- Jun 79° 54°
- Jul 84° 57°
- Aug 81° 57°
- Sep 74° 48°
- Oct 62° 38°
- Nov 48° 30°
- Dec 36° 22°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Ann Arbor each month?
July is the warmest month, with normal highs of 84°F; January the coldest, with normal lows of 15°F. The most precipitation falls in June (3.61 in), the least in February (1.51 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 32°F | 15°F | 23.5°F | 1.68 | 10 | <1 | 29 | 9 h 20 min |
| February | 35°F | 16°F | 25.3°F | 1.51 | 9 | <1 | 26 | 10 h 30 min |
| March | 45°F | 25°F | 35.3°F | 1.95 | 10 | <1 | 24 | 11 h 50 min |
| April | 59°F | 35°F | 47.0°F | 3.03 | 12 | <1 | 12 | 13 h 20 min |
| May | 70°F | 46°F | 57.8°F | 3.35 | 14 | <1 | 3 | 14 h 30 min |
| June | 79°F | 54°F | 66.4°F | 3.61 | 11 | 2 | <1 | 15 h 10 min |
| July | 84°F | 57°F | 70.5°F | 3.20 | 11 | 5 | <1 | 15 h |
| August | 81°F | 57°F | 69.2°F | 2.69 | 12 | 2 | <1 | 14 h |
| September | 74°F | 48°F | 61.3°F | 2.76 | 12 | 1 | 1 | 12 h 30 min |
| October | 62°F | 38°F | 49.9°F | 2.22 | 12 | <1 | 10 | 11 h 10 min |
| November | 48°F | 30°F | 38.7°F | 2.09 | 10 | <1 | 20 | 9 h 50 min |
| December | 36°F | 22°F | 28.9°F | 1.69 | 11 | <1 | 27 | 9 h 10 min |
| Year (annual) | 59°F | 37°F | 47.8°F | 29.78 | 134 | 11 | 150 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 0°C | −9°C | −4.7°C | 43 mm |
| February | 1°C | −9°C | −3.7°C | 38 mm |
| March | 7°C | −4°C | 1.8°C | 50 mm |
| April | 15°C | 2°C | 8.3°C | 77 mm |
| May | 21°C | 8°C | 14.3°C | 85 mm |
| June | 26°C | 12°C | 19.1°C | 92 mm |
| July | 29°C | 14°C | 21.4°C | 81 mm |
| August | 27°C | 14°C | 20.7°C | 68 mm |
| September | 23°C | 9°C | 16.3°C | 70 mm |
| October | 16°C | 3°C | 9.9°C | 56 mm |
| November | 9°C | −1°C | 3.7°C | 53 mm |
| December | 2°C | −6°C | −1.7°C | 43 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Ann Arbor's own co-op station Ann Arbor SE does: 59 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094889; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Ann Arbor?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (11).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094889.
When is the last frost in Ann Arbor?
In Ann Arbor, the last spring frost (32°F) comes after May 8 in half of years and after May 26 in one year in ten; the first autumn frost comes before October 4 in half of years and before September 20 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 81 year in 10 after May 26; 9 in 10 after April 23
- First autumn frost, half of years before
- October 41 year in 10 before September 20; 9 in 10 before October 17
NOAA puts the median frost-free season at 147 days, and the season without a hard freeze (28°F) at 169 days.
A hard freeze (28°F) comes after April 27 in half of springs and before October 16 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Ann Arbor in zone 6a across its 5 ZIP code areas (6a in 48103, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Ann Arbor's NOAA station is in zone 5b: the coldest night of a typical year reaches −14°F (21 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Michigan · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00094889; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Ann Arbor ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Ann Arbor's 5 ZIP code areas are all in zone 6a. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Ann Arbor?
In a normal year in Ann Arbor, 11 days a year reach 90°F, 150 nights fall to 32°F or colder and 134 days bring measurable precipitation.
- Days at 90°F or more
- 11a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 150a normal year
- Days that stay below freezing
- 47high of 32°F or less
- Days with 0.01 inch of precipitation
- 134a normal year
The highest temperature in this station's record (since 1998) is 102°F, on June 28, 2012; the lowest is −30°F, on February 20, 2015.
The wettest calendar year on that record is 2006, with 35.22 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00094889; records: ACIS (NOAA Regional Climate Centers), station USW00094889. Records use complete months only; a month missing more than three days is left out.
How sunny is Ann Arbor?
Over a year 71% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Ann Arbor, 3.8 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (54%). Among the 459 U.S. places of 50,000 or more, that ranks tied 416th (with 11 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 59% | 1.6 |
| February | 62% | 2.4 |
| March | 66% | 3.5 |
| April | 68% | 4.7 |
| May | 70% | 5.5 |
| June | 76% | 6.2 |
| July | 80% | 6.2 |
| August | 78% | 5.3 |
| September | 77% | 4.3 |
| October | 68% | 2.8 |
| November | 63% | 1.8 |
| December | 54% | 1.2 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Ann Arbor need?
A normal year in Ann Arbor brings 6,742 heating degree days, 25% more than the median U.S. place (5,373), and 520 cooling degree days, 43% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,545 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,286 | 0 |
| February | 1,112 | 0 |
| March | 920 | 0 |
| April | 542 | 2 |
| May | 249 | 28 |
| June | 59 | 102 |
| July | 15 | 186 |
| August | 22 | 150 |
| September | 157 | 46 |
| October | 474 | 6 |
| November | 789 | 0 |
| December | 1,118 | 0 |
| Year (annual) | 6,742 | 520 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094889. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Ann Arbor been warmer than normal lately?
2025 averaged 48.0°F, 0.2°F above the 1991-2020 normal of 47.8°F. 3 of the 4 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2022 | 47.7°F | −0.1°F | 26.01 |
| 2023 | 49.4°F | +1.6°F | 26.85 |
| 2024 | 51.0°F | +3.2°F | 33.17 |
| 2025 | 48.0°F | +0.2°F | – |
Source: observed years: ACIS, station USW00094889. A year counts only with all twelve months complete.
How does Ann Arbor's climate compare?
Ann Arbor is warmer than 94 of the other 139 places with their own NOAA record in Michigan, and wetter than 9. Across the 7,247 U.S. stations with normals, its annual mean of 47.8°F is warmer than 31%.
In the Köppen classification computed from these normals, Ann Arbor is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
What do Ann Arbor's other NOAA stations record?
2 more NOAA stations keep 1991-2020 normals in or near Ann Arbor. This page uses Ann Arbor Municipal Airport; the others differ by site and elevation, and the linked ones have pages of their own:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Ann Arbor SE USC00200228 | 3 mi SE | 832 ft | 48.2°F | 16°F | 84°F | 37.9 | 59 | May 5 |
| Ann Arbor University of Michigan USC00200230 | 4 mi NE | 813 ft | 48.8°F | 16°F | 84°F | 38.3 | 61 | May 3 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Ann Arbor's climate
What is the coldest month in Ann Arbor?
January, with a normal high of 32°F and a normal low of 15°F. The warmest is July (84°F by day, 57°F at night).
Does it snow in Ann Arbor?
Yes. NOAA publishes no 1991-2020 snowfall normal for Ann Arbor's NOAA station; Ann Arbor's own co-op station Ann Arbor SE records 59 inches of snow in a normal year.
What is the rainiest month in Ann Arbor?
June, with 3.61 in of precipitation in a normal year; the driest is February with 1.51 in.
What plant hardiness zone is Ann Arbor in?
The USDA's 2023 map puts Ann Arbor in zone 6a across its 5 ZIP code areas (6a in 48103, the largest). By the same method at Ann Arbor's NOAA station, the coldest night of a typical year reaches −14°F (21 years, 1991-2020): zone 5b.
How late can frost come in Ann Arbor?
In half of years the last 32°F night comes after May 8; in one year in ten it comes after May 26. Waiting until May 26 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Ann Arbor in OctoberThis month day by day, its records and recent years
- Michigan climateThe statewide normals and every place in the state
- Ann Arbor SE, MI3 miles from this station, 48.2°F a year
- Saline, MI5 miles from this station, 48.2°F a year
- Ann Arbor University of Michigan, MI7 miles from this station, 48.8°F a year
- Milan, MI11 miles from this station, 49.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made