Climate averages 1991–2020
Ann Arbor weather
in September.
A warm, moderately wet month: the 4th warmest and the 7th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Ann Arbor: daytime highs average 22.3°C and nights cool to about 13.3°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 69 mm of rain on roughly 9 days, which makes September a moderately wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 32 min on an average September day.
The nearest other city in this atlas is Canton (Michigan), United States (22 km away). In September its highs average 22.6°C, about as warm as Ann Arbor, with 68 mm of rain.
Among the 498 cities listed in the United States, Ann Arbor ranks joint 442nd of 498 for the warmest September highs and joint 209th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Ann Arbor is 4.6°C cooler than that mean.
From September to October, average highs fall by 7.0°C to 15.3°C, and monthly rainfall falls from 69 mm to 68 mm.
The annual picture
September in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Ann Arbor climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -0.6°C-8.3°C | -8.3°C | 61 | 9.7 | 9.59 h |
| February | 1.0°C-7.9°C | -7.9°C | 53 | 8.3 | 10.511 h |
| March | 6.7°C-3.1°C | -3.1°C | 65 | 9.6 | 11.912 h |
| April | 13.5°C3.0°C | 3.0°C | 92 | 11.8 | 13.313 h |
| May | 19.8°C9.7°C | 9.7°C | 99 | 12.5 | 14.615 h |
| June | 24.8°C15.2°C | 15.2°C | 93 | 10.5 | 15.215 h |
| July | 27.0°C17.7°C | 17.7°C | 84 | 10.8 | 14.915 h |
| August | 26.0°C17.1°C | 17.1°C | 83 | 10.3 | 13.914 h |
| September, selected | 22.3°C13.3°C | 13.3°C | 69 | 8.6 | 12.513 h |
| October | 15.3°C7.1°C | 7.1°C | 68 | 9.3 | 11.111 h |
| November | 8.0°C0.8°C | 0.8°C | 67 | 9.0 | 9.810 h |
| December | 2.0°C-4.3°C | -4.3°C | 57 | 9.0 | 9.29 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Canton (Michigan), United States in SeptemberUnited States · 22 kmHigh 22.6°C · Low 13.7°C · 68 mm rain
- Westland in SeptemberUnited States · 28 kmHigh 22.6°C · Low 13.9°C · 68 mm rain
- Livonia in SeptemberUnited States · 33 kmHigh 22.7°C · Low 14.1°C · 69 mm rain
- Farmington Hills in SeptemberUnited States · 38 kmHigh 22.3°C · Low 13.7°C · 71 mm rain
- Dearborn in SeptemberUnited States · 47 kmHigh 22.6°C · Low 14.3°C · 69 mm rain
- Southfield in SeptemberUnited States · 48 kmHigh 22.4°C · Low 14.2°C · 70 mm rain
- Waterford in SeptemberUnited States · 54 kmHigh 22.0°C · Low 13.6°C · 73 mm rain
- Detroit in SeptemberUnited States · 57 kmHigh 22.3°C · Low 14.9°C · 67 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Ann Arbor) is explained once on the Ann Arbor year overview and on the Sources, method and limits page.