Climate averages 1991–2020
Duluth weather
in September.
A mild, 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 mild month in Duluth: daytime highs average 19.5°C and nights cool to about 13.8°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 92 mm of rain on roughly 11 days, which makes September a wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 36 min on an average September day.
The nearest other city in this atlas is Brooklyn Park (211 km away). In September its highs average 21.6°C, 2.1°C warmer than Duluth, with 84 mm of rain.
Among the 498 cities listed in the United States, Duluth ranks 496th of 498 for the warmest September highs and joint 350th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Duluth is 7.4°C cooler than that mean.
From September to October, average highs fall by 7.9°C to 11.6°C, and monthly rainfall rises from 92 mm to 103 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
Duluth climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -7.2°C-13.9°C | -13.9°C | 26 | 6.3 | 9.09 h |
| February | -5.2°C-12.0°C | -12.0°C | 28 | 5.4 | 10.310 h |
| March | 0.5°C-6.1°C | -6.1°C | 49 | 7.3 | 11.912 h |
| April | 6.5°C-0.2°C | -0.2°C | 84 | 10.2 | 13.614 h |
| May | 13.4°C6.5°C | 6.5°C | 97 | 11.1 | 15.015 h |
| June | 19.6°C13.2°C | 13.2°C | 105 | 11.6 | 15.816 h |
| July | 23.9°C17.8°C | 17.8°C | 98 | 11.7 | 15.515 h |
| August | 23.6°C17.8°C | 17.8°C | 102 | 10.5 | 14.214 h |
| September, selected | 19.5°C13.8°C | 13.8°C | 92 | 10.6 | 12.613 h |
| October | 11.6°C6.6°C | 6.6°C | 103 | 10.8 | 10.911 h |
| November | 3.6°C-1.1°C | -1.1°C | 66 | 8.9 | 9.49 h |
| December | -3.2°C-8.8°C | -8.8°C | 45 | 7.5 | 8.69 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
- Brooklyn Park in SeptemberUnited States · 211 kmHigh 21.6°C · Low 13.3°C · 84 mm rain
- Saint Paul in SeptemberUnited States · 218 kmHigh 21.8°C · Low 13.4°C · 86 mm rain
- Minneapolis in SeptemberUnited States · 220 kmHigh 21.8°C · Low 13.4°C · 84 mm rain
- Plymouth, United States in SeptemberUnited States · 223 kmHigh 21.5°C · Low 13.3°C · 82 mm rain
- Bloomington (Minnesota), United States in SeptemberUnited States · 235 kmHigh 21.9°C · Low 13.8°C · 82 mm rain
- Thunder Bay in SeptemberCanada · 278 kmHigh 17.8°C · Low 11.7°C · 84 mm rain
- Rochester (Minnesota), United States in SeptemberUnited States · 308 kmHigh 21.4°C · Low 12.9°C · 84 mm rain
- Fargo in SeptemberUnited States · 356 kmHigh 20.9°C · Low 11.4°C · 72 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 Duluth) is explained once on the Duluth year overview and on the Sources, method and limits page.