Iowa Monthly Weather Summary – September 2025
General Summary
Preliminary statewide temperatures averaged 67.1 degrees or 3.4 degrees above normal while precipitation totaled 1.70 inches or 1.78 inches below normal. Preliminarily, September 2025 ties 1906 as the 21st warmest in 153 years of statewide records; it also ranks as the 21st driest. September 2023 was warmer while last September was drier and the driest in record.
Temperatures
Statewide average temperatures in September were above average across all of Iowa with the warmest conditions found in pockets from central to northwest Iowa. Davenport (Scott County) reported the month’s high temperature of 99 degrees on the 13th, 22 degrees above normal. Stanley (Buchanan County) reported the month’s low temperature of 32 degrees on the 7th, which was 19 degrees below normal.
Cooling Degree Days
Home air conditioning requirements, as estimated by cooling degree day totals, averaged 4% more than last September and 55% more than normal. Cooling degree day totals since January are running 5% more than last year at this time and 15% more than normal.
Precipitation
Much of Iowa reported precipitation deficits through September with the driest conditions across eastern and northwest Iowa; these deficits were at or above two inches. Swaths of stations in western Iowa reported positive departures in the range of one to two inches. Monthly precipitation totals ranged from 0.22 inch in Davenport to 8.24 inches in Mondamin (Harrison County).
US Drought Monitor
Abnormal dryness (D0) was reintroduced across southern Iowa during the first week of September, reflective of a drier than normal August. There was some imorovement across south-central Iowa in the middle of the month, however, D0 returned and expanded across northwestern Iowa. As of the first week of October, about 49% of Iowa is rated as Abnormally Dry (D0), with a small pocket of D1 (Moderate Drought) along the Iowa-Illinois border.
Note
Due to the ongoing Federal government shutdown, data should be treated as preliminary until full quality-control has been completed. This report will be updated at a future date.
Justin Glisan, Ph.D.
State Climatologist of Iowa
Iowa Dept. of Agriculture & Land Stewardship
Wallace State Office Bldg.
Des Moines, IA 50319
Telephone: (515) 281-8981
E-mail: Justin.Glisan@IowaAgriculture.gov
Weather by Districts
| TEMPERATURE (F) | COOLING DEGREE DAYS | PRECIPITATION (inches) | ||||||||
| September 2025 | September 2025 | Since Jan., 1, 2025 | September 2025 | Since Jan.1, 2025 | ||||||
| DISTRICT | Average | Departure* | Average | Departure* | Average | Departure* | Average | Departure* | Average | Departure* |
| Northwest | 66.0 | +3.5 | 101 | +92 | 814 | +287 | 1.25 | -1.90 | 26.00 | +0.66 |
| North Central | 65.5 | +3.3 | 90 | +83 | 768 | +302 | 2.32 | -1.05 | 29.80 | +3.91 |
| Northeast | 65.3 | +3.2 | 87 | +80 | 741 | +294 | 1.74 | -2.06 | 31.59 | -0.49 |
| West Central | 66.7 | +3.0 | 109 | +89 | 923 | +291 | 3.23 | -0.02 | 28.02 | +2.93 |
| Central | 67.4 | +3.6 | 123 | +101 | 952 | +334 | 2.09 | -1.37 | 30.17 | +2.90 |
| East Central | 67.7 | +3.6 | 135 | +109 | 984 | +346 | 0.97 | -2.68 | 30.75 | -2.77 |
| Southwest | 68.2 | +3.2 | 136 | +97 | 1028 | +253 | 2.09 | -1.36 | 29.71 | -5.74 |
| South Central | 68.9 | +3.9 | 154 | +114 | 1083 | +320 | 2.38 | -1.31 | 30.84 | -2.69 |
| Southeast | 69.1 | +3.7 | 162 | +116 | 1119 | +331 | 1.57 | -2.05 | 31.03 | -3.66 |
| STATE | 67.1 | +3.4 | 120 | +46 | 926 | +123 | 1.70 | -1.78 | 29.69 | -0.49 |
* Departures are computed from 1991-2020 normals. Due to the federal government shutdown, observations are still preliminary.
The weather data in this report are based upon information collected by the U. S. Dept. of Commerce, NOAA National Weather Service.
