Climate averages 1991–2020
Sioux City weather
in September.
A warm, moderately wet month: the 4th warmest and the joint 7th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Sioux City: daytime highs average 23.8°C and nights cool to about 13.8°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 75 mm of rain on roughly 8 days, which makes September a moderately wet month (the joint 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 Sioux Falls (119 km away). In September its highs average 22.6°C, 1.1°C cooler than Sioux City, with 80 mm of rain.
Among the 498 cities listed in the United States, Sioux City ranks joint 366th of 498 for the warmest September highs and joint 246th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Sioux City is 3.1°C cooler than that mean.
From September to October, average highs fall by 7.7°C to 16.1°C, and monthly rainfall falls from 75 mm to 61 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
Sioux City climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.9°C-11.2°C | -11.2°C | 23 | 4.7 | 9.49 h |
| February | 1.1°C-9.0°C | -9.0°C | 27 | 5.1 | 10.511 h |
| March | 8.2°C-2.7°C | -2.7°C | 55 | 7.0 | 11.912 h |
| April | 15.0°C3.9°C | 3.9°C | 101 | 10.6 | 13.313 h |
| May | 21.0°C10.6°C | 10.6°C | 126 | 12.6 | 14.615 h |
| June | 26.3°C16.5°C | 16.5°C | 123 | 11.8 | 15.215 h |
| July | 28.7°C19.3°C | 19.3°C | 75 | 8.8 | 15.015 h |
| August | 27.5°C18.1°C | 18.1°C | 98 | 9.4 | 13.914 h |
| September, selected | 23.8°C13.8°C | 13.8°C | 75 | 7.6 | 12.513 h |
| October | 16.1°C6.5°C | 6.5°C | 61 | 7.3 | 11.111 h |
| November | 7.6°C-1.3°C | -1.3°C | 40 | 5.4 | 9.810 h |
| December | 0.3°C-8.0°C | -8.0°C | 30 | 5.2 | 9.19 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
- Sioux Falls in SeptemberUnited States · 119 kmHigh 22.6°C · Low 12.8°C · 80 mm rain
- Omaha in SeptemberUnited States · 143 kmHigh 24.8°C · Low 14.8°C · 77 mm rain
- Lincoln in SeptemberUnited States · 190 kmHigh 25.5°C · Low 15.2°C · 71 mm rain
- Des Moines in SeptemberUnited States · 251 kmHigh 23.9°C · Low 14.3°C · 90 mm rain
- Saint Joseph in SeptemberUnited States · 330 kmHigh 25.2°C · Low 15.7°C · 85 mm rain
- Rochester (Minnesota), United States in SeptemberUnited States · 360 kmHigh 21.4°C · Low 12.9°C · 84 mm rain
- Bloomington (Minnesota), United States in SeptemberUnited States · 360 kmHigh 21.9°C · Low 13.8°C · 82 mm rain
- Plymouth, United States in SeptemberUnited States · 366 kmHigh 21.5°C · Low 13.3°C · 82 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 Sioux City) is explained once on the Sioux City year overview and on the Sources, method and limits page.