Ann Arbor, Michigan Weather
Day 93 of summer. Read today’s microseason across nine climate regions →
Ann Arbor weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 10:22 AM EDT · Open-Meteo
- TodaySep 21Overcast——63°53°—
- TuesdaySep 22Overcast——63°47°0°
- WednesdaySep 23Light Rain23%0.18″61°53°-2°
- ThursdaySep 24Overcast——69°51°+8°
- FridaySep 25Overcast——70°50°+1°
- SaturdaySep 26Overcast——72°49°+2°
- SundaySep 27Light Drizzle—0.01″62°56°-10°
Air quality now AQI 46 · Good
AQI 46 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±4 points). PM2.5 at 7.4 µg/m³, PM10 at 7.7 µg/m³ — typical background levels with no transport signature.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 7.4 µg/m³, PM10 at 7.7 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.96
- Wind
- breezy
- Recent rain
- 0h in last 6h
- Pattern
- background
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
September dries up ditches or breaks down bridges.
- Moonrise
- 5:14 PM
- Moonset
- 1:47 AM
- In sign
- ♑︎ Capricorn
Ann Arbor at a glance
- Today vs. normal: Today averages 58°F (high 63°F, low 53°F), 2°F below the 60°F normal for Sep 21
- Last frost: May 5 (1991–2020 median, NOAA station 5 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash
16-Day Forecast — Ann Arbor
- Mon63°53°3%
- Tue63°47°6%
- Wed61°53°23%
- Thu69°51°6%
- Fri70°50°1%
- Sat72°49°0%
- Sun62°56°2%
- Mon72°56°5%
- Tue81°56°17%
- Wed74°56°21%
- Thu68°50°21%
- Fri62°44°10%
- Sat80°54°25%
- Sun66°49°12%
- Mon57°41°23%
- Tue56°35°19%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Ann Arbor
Interactive wind and temperature map centered on Ann Arbor — it loads in your browser. Open the full weather map.
Right now in the garden
Fall planting + final harvests
As of September 21, the season's first frost (typically October 10) is approaching. Pick what frost-tender plants still carry before the next cold front. This city's planting calendar for September: plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in Ann Arbor
Ann Arbor sits in Washtenaw County, where the year’s longest day runs 15h 16m of daylight and its shortest just 9h 5m — a swing of +6h 12m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Detroit, the state’s largest city, lies about 33 miles to the ENE. The nearest town Ann Arbor tracks is South Lyon, roughly 13 miles to the NNE.
Air quality in Ann Arbor
Air quality in Ann Arbor’s county has held roughly steady since 2020; its cleanest year on record was 2025 (median AQI 41). See the full air-quality history for Ann Arbor.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, spinach, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| July | beans, squash, fall brassicas, carrots | lettuce, peas, spinach, beans, summer squash, garlic |
| August | — | peas, tomatoes, peppers, beans, summer squash, garlic |
| September | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| October | — | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| November | — | fall brassicas, carrots |
A year in weather
July is Ann Arbor's warmest stretch (~72°F) and January its coldest (~24°F); precipitation crests in June at 4.3 inches and ebbs in February to 2.4 inches.
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 24° | 2.8″ | 8 |
| February | 26° | 2.4″ | 6 |
| March | 35° | 2.8″ | 6 |
| April | 46° | 3.3″ | 7 |
| May | 58° | 3.8″ | 8 |
| June | 68° | 4.3″ | 7 |
| July | 72° | 3.9″ | 7 |
| August | 70° | 3.3″ | 6 |
| September | 62° | 3.0″ | 6 |
| October | 51° | 2.9″ | 7 |
| November | 39° | 2.7″ | 7 |
| December | 29° | 2.6″ | 7 |
Regional context
Similar climates Barton Hills, MI, Ypsilanti, MI, Saline, MI
By the nearest station's NOAA NCEI 1991-2020 normals, Ann Arbor sees 24°F Januarys and 72°F Julys, a 48°F range, plus around 37.9 inches of precipitation across 82 days.
Ann Arbor's precipitation spreads evenly across the seasons: June peaks at 4.3 inches on 6.9 wet days, while February holds 2.4 inches over 6.2 — no season dominates Ann Arbor's rain calendar. It is a balanced pattern Ann Arbor shares with places like Barton Hills, MI, Ypsilanti, MI and Saline, MI.
By May 5 the frosts ease in Ann Arbor, opening the season for kale, peas, spinach, and parsnips. In Ann Arbor, warm-season transplants — tomatoes, peppers, basil — wait two weeks past Ann Arbor's frost date. Around October 10, freezing nights resume in Ann Arbor and tender crops must come in. Sheltered Ann Arbor yards can escape a light frost.
Similar climates: Barton Hills, MI, Ypsilanti, MI, Saline, MI, Dexter, MI, Whitmore Lake, MI.
Frequently asked
- When does it freeze in Ann Arbor?
- Ann Arbor's last spring frost lands near May 5, and in Ann Arbor the first fall frost follows around October 10.
- What is the rainy season in Ann Arbor?
- Ann Arbor sees its heaviest rain in June (around 4.3 inches), part of roughly 38 inches a year.
- What is the warmest month in Ann Arbor?
- Ann Arbor peaks in July, when the mean runs near 72°F.
- What is the coldest month in Ann Arbor?
- January is Ann Arbor's coldest month, averaging about 24°F.
- When can I start a vegetable garden in Ann Arbor?
- Around May 5, start frost-hardy crops in Ann Arbor; tomatoes and basil belong a fortnight later.
- How many rainy days does Ann Arbor get?
- Ann Arbor averages about 82 days with measurable rain or snow each year.
- What hardiness zone is Ann Arbor?
- Since January in Ann Arbor averages 24°F, Ann Arbor's USDA zone follows that floor — confirm it by ZIP.
- What is the 10-day forecast for Ann Arbor?
- Ann Arbor's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Ann Arbor?
- See this week's day-by-day rain chances for Ann Arbor in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Ann Arbor?
- Current conditions for Ann Arbor and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Ann Arbor forecast updated?
- The Ann Arbor forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Ann Arbor?
- Today's sunrise and sunset times for Ann Arbor are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Ann Arbor?
- The next few days in Ann Arbor's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Ann Arbor sits at 42.3°N; its climate zone is warm-summer humid continental (Köppen approximation).
ZIP codes in Ann Arbor
- 48103
- 48104
- 48105
- 48108
- 48109
- 48113