Iowa Weekly Growing Season Report

Preliminary weather summary for the week June 15-21, 2026

A less active pattern compared to previous weeks brought one day of severe weather and then widespread, spring-like rainfall by the end of the week. Rainfall totals were highest over southeast Iowa. A shift to cooler temperatures also greeted Iowans with negative departures approaching seven degrees; the statewide average temperature was 67.8 degrees, 4.3 degrees below normal.

Chilly northwesterly winds and stratocumulus clouds slowly gave way to pleasant conditions through Sunday (14th) afternoon. Temperatures pushed into the upper 60s and low 70s as winds became gustier under mostly sunny skies. Winds died down and turned westerly overnight into Monday (15th) under starry conditions and morning lows in the 50s. Daytime temperatures were near-seasonal, warming into the upper 70s with spotty cloud cover. Showers and a few thunderstorms pushed across the state from the evening to overnight hours as a weak cold front swept southeast. Most stations that had measurable totals observed less than 0.10 inch, though West Point (Lee County) registered 0.17 inch. Winds swung back around to the northwest, becoming gusty into Tuesday (16th) afternoon with clouds clearing in eastern Iowa and temperatures in the mid to upper 70s. Winds turned southerly towards midnight as a strong low pressure disturbance propagated along the Iowa-Minnesota border towards sunrise. Initial thunderstorms in northwest Iowa coalesced into a line along the low’s attendant cold front and quickly strengthened over north-central Iowa. As a strong rear-inflow jet pushed into the center of the line, the squall bowed out and intensified. Heavy rain and severe wind gusts were reported along the path from 64 mph near Storm Lake (Buena Vista County) to 75 mph in Walford (Linn County); the strongest gust of 94 mph was observed near Marshalltown (Marshall County), producing crop and structural damage. The line increased in aerial extent in southeastern Iowa where widespread flash flood warnings were issued. The complex exited eastern Iowa around noon on Wednesday (17th). Additional severe thunderstorms fired in northeastern Iowa by the late afternoon hours, producing a longer track EF-2 rated tornado in Elon (Allamakee County) which crossed the Mississippi River into Wisconsin. A swath of stations from north-central to eastern Iowa reported higher totals with nearly 130 stations hitting at least 1.00 inch; more than 25 stations picked up more than 2.00 inches with 2.55 inches in Ely (Linn County) to 2.95 inches in Story City (Story County). Notably, four stations in Muscatine County reported totals from 3.25-4.33 inches.

Thursday (18th) dawned with clouds north and clear skies south with morning lows in the upper 50s to low 60s. Cloud cover increased over the state with afternoon temperatures holding in the mid 70s. Clear skies persisted into Friday (19th) with calm winds and morning temperatures in the low 50s north to low 60s south. Scattered showers crossed the state through the daytime hours as another cold front moved through Iowa. Behind the front, temperatures were in the low 60s while upper 70s were found in southeast Iowa. Rain totals reported at 7:00 am on Saturday (20th) were generally light, though airports in Ames (Story County) and Waterloo (Black Hawk County) registered 0.23 inch and 0.41 inch, respectively. Afternoon conditions were pleasant with ample sunshine and highs in the mid to upper 70s. Clouds increased over southwestern Iowa around sunset as moderate showers spun into the state. Showers overspread southern Iowa into Sunday (21st) where most southwest stations collected between 0.75 to 1.50 inches; Council Bluffs (Pottawattamie County) received between 2.98 to 3.09 inches at two stations.

Weekly precipitation totals ranged from a trace near Carroll (Carroll County) to 4.41 inches in Muscatine (Muscatine County). The statewide weekly average precipitation was 1.66 inches; the normal is 1.20 inches. Lamoni (Decatur County) reported the week’s high temperature of 89 degrees on the 17th, five degrees above normal. Airports in Sioux City (Woodbury County) and Spencer (Clay County) reported the week’s low temperature of 43 degrees on the 15th, on average 16 degrees below normal.