Monthly Weather Report

Iowa Monthly Weather Summary – August 2026

General Summary

Statewide temperatures averaged 71.9 degrees or 0.9 degree above normal while precipitation totaled 4.79 inches or 0.66 inch above normal. August 2026 ties 1921 and 2020 as the 75th warmest on record and ranks as the 36th wettest on record. A warmer August last occurred in 2023 while 2021 was wetter.

Temperatures

Statewide average temperatures in August were above average across all of Iowa with the warmest conditions found in pockets from central to northwest Iowa. Lamoni (Decatur County) reported the month’s high temperature of 96 degrees on the 31st, 13 degrees above normal. Lake Park (Dickinson County) and Spencer Municipal Airport (Clay County) reported the month’s lowest temperature of 47 degrees on the 23rd, on average 12 degrees below normal.

Cooling Degree Days

Home cooling requirements, as estimated by cooling degree day totals, were 17% more than last August and 9% more than normal. Cooling degree day totals since January are 3% more than last year at this time and 15% more than normal.

Precipitation

While the statewide average rainfall was above normal, a majority of the state had near to below normal amounts. Northwest Iowa was the driest part of the state with deficits in the 1.00-3.00 inch range. Stations from west-central and southeast Iowa reported totals in in the 200-300% of normal range. Monthly precipitation totals ranged from 1.59 inch at Dubuque Regional Airport (Dubuque County) to 13.95 inches in Wapello (Louisa County).

August precipitation was characterized by frequent, heavy rainfall events rather than a steady distribution of precipitation. Several rounds of thunderstorms and mesoscale convective systems (MCS) produced widespread rainfall, with particularly significant events early and during the middle of the month. The heaviest rainfall was often concentrated in eastern, southern, and central Iowa, with multiple stations recording more than 2.00 inches during individual events.

The first half of August was notably wet and stormy, with repeated thunderstorm complexes producing flash flooding and several episodes of severe weather. Heavy rainfall continued through August 15–16, including another concentrated event in southeastern Iowa, before conditions became considerably quieter through much of the latter half of the month. Late-month rainfall was generally lighter, with a statewide average of only 0.22 inch on August 29, although most stations received measurable precipitation and isolated totals exceeded 1.00 inch. Overall, the month's precipitation pattern was defined by highly efficient, episodic rainfall with substantial spatial variability, including periods of very heavy rain separated by relatively dry stretches

Summer Summary

Temperatures for the three summer months of June, July and August averaged 72.7 degrees, which is 1.3 degrees above normal. Precipitation totaled 14.32 inches or 0.76 inch above normal. This ties 1940 and 1984 as the 54th warmest summer on record. It also ranks as the 39th wettest summer in 154 years of records. Summer 2021 was warmer while 2025 was wetter and the 6th wettest on record.

Severe weather

Severe weather was frequent and widespread during the first half of August, with multiple rounds of organized thunderstorms producing damaging winds, large hail, tornadoes and very heavy rainfall. The most significant event occurred on August 7, when a strong cold front and an unstable, moisture-rich atmosphere supported a severe thunderstorm complex across north-central and eastern Iowa. The event produced an EF-2 tornado near Fairbank (Buchanan County) and an EF-1 tornado near Prairieburg (Linn County), along with locally heavy rainfall. Additional severe storms followed on August 10–13, including a derecho-producing squall line on August 11 that generated a 75-mph wind gust at Independence (Buchanan County) and two EF-1 tornadoes near Greeley (Delaware County).

The active pattern continued through August 13–16, as repeated MCSs crossed the state. The August 13 complex produced several severe- and tornado-warned storms, strong winds, and torrential rainfall, while additional storms that night produced training rainfall and flash flooding. Severe weather became less prominent during the latter half of the month, although thunderstorms returned late in the month as another complex moved across Iowa on August 29–30. Overall, the month's severe weather was concentrated heavily in the first two weeks, characterized by repeated organized thunderstorm complexes, multiple tornadoes, damaging winds, and substantial overlap between severe weather and extreme rainfall.

US Drought Monitor (USDM)

As of August 4th, more than 26% of Iowa was classified as in at least Moderate Drought (D1) with less than 1% in Severe Drought (D2). Abnormally Dry (D0) covered 18% of the state. The following week, a pocket of D2 was introduced in west-central Iowa, where precipitation deficits were approaching 55% of normal. An active stretch of wet weather across western Iowa allowed for D1 and D2 conditions to be reduced on the USDM map released on the 18th. As of September 1st, 20% of Iowa was in D1 or D2 conditions, with less than 1% classified as D2.  According to the Iowa Drought Plan (IDP) trigger tables updated on September 10th, Drought Regions 1 and 2 remain classified as in a “Watch” with degrading conditions in Drought Region 3.

Justin Glisan, Ph.D.
State Climatologist of Iowa
Iowa Dept. of Agriculture & Land Stewardship
Hoover State Office Bldg.
Des Moines, IA 50319
Telephone: (515) 281-8981
E-mail: [email protected]

WEATHER BY DISTRICTS

* Departures are computed from 1991-2020 normals.                                        
The weather data in this report are based upon information collected by the U. S. Dept. of Commerce, NOAA National Weather Service.