Ann Arbor, MI weather in September
In September, Ann Arbor sees highs around 75°F and lows around 52°F: mild, with frequent rain. Rain falls on about 11 days. Good for outdoor plans.
- Normal high
- 75°F
- Normal low
- 52°F
- Wet days
- 11
- 3.2 in total
- Muggy days
- 3
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 80°F | 70°F |
| Normal low | 56°F | 46°F |
| Chance of a wet day | 35% | 38% |
| Sunrise / sunset | 7:00 am / 8:09 pm | 7:31 am / 7:18 pm |
| Daylight | 13.2 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Eastern Time).
A typical September day
- 6 am56°Fdew point 52°F
- 9 am64°Fdew point 56°F
- Noon72°Fdew point 55°F
- 3 pm74°Fdew point 54°F
- 6 pm70°Fdew point 55°F
- 9 pm62°Fdew point 55°F
NOAA hourly normals (local standard time) from Detroit Willow Run Airport (10 mi away); average wind 7 mph; clear or few clouds in 60% of daytime hours, mostly cloudy or overcast in 31%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F16 of 30
- Hot dayshigh 90°F or more1 of 30
- Muggy daysdaily mean dew point 65°F or more3 of 30
- Wet daysat least 0.01 in of rain or melted snow11 of 30
- Notable rainat least 0.10 in6 of 30
- Freezing nightslow 32°F or below0 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 3.2 in; a dry September brings about 1.9 in and a wet one about 4.6 in (25th and 75th percentiles). About 2 days bring half an inch or more, and about 1 an inch or more.
How September varies from year to year
- Warmest September, 1991-20202002: average high 81°F
- Coolest September1993: average high 67°F
- Wettest September2008: 6.1 in
- Driest September2004: 0.8 in
- Highest reading96°F (September 2, 2011)
- Lowest reading29°F (September 19, 2020)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 82°F | 75°F | 62°F |
| Normal low | 59°F | 52°F | 41°F |
| Wet days | 11 | 11 | 13 |
| Comfortable days | 9 | 16 | 11 |
| Daylight | 13.8 h | 12.5 h | 11.1 h |
Highs change by -7°F from August and -13°F into October.
Nearby alternatives in September
- Drier: Carmel, IN201 mi · high 77°F · 7 wet days
How Ann Arbor ranks in September
- Normal high279th warmest of 378 cities; 1st of 8 in Michigan
- Wet days325th driest of 378
- Comfortable days51st most of 342
What to pack for Ann Arbor in September
- A rain jacket or umbrella – rain on about 11 days
Heating and cooling
September has 118 heating degree days and 69 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Ann Arbor in September?
The normal high is 75°F and the normal low is 52°F. From 1991 to 2020 the hottest September reading was 96°F (September 2, 2011).
Does it rain a lot in Ann Arbor in September?
About 11 days in September have at least 0.01 in of precipitation, and the normal total is 3.2 in. The wettest September in 1991-2020 was in 2008 (6.1 in); the driest was in 2004 (0.8 in).
Is September a good time to visit Ann Arbor?
September ranks 2nd of 12 months on our comfort score for Ann Arbor (69 out of 100). It has about 16 comfortable days and about 1 day at 90°F or hotter. The best month is May.
Where the numbers come from
- Temperature, rain, snowfall, snow depth and frost dates: Ann Arbor U Of Mich (USC00200230), 3.7 mi ENE of the city center, 813 ft (68 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour: Detroit Willow Run Airport (USW00014853), 10 mi ESE of the city center, 777 ft (104 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Cloud cover: Toledo Express Airport (USW00094830), 47 mi S of the city center, 669 ft (212 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Willow Run Airport (725376-14853), 11 mi ESE of the city center, 708 ft (173 ft lower than the city). Hourly observations, 1991-2020.