Iowa Preliminary Weather Summary

Provided by Justin Glisan, Ph.D., State Climatologist Iowa Department of Agriculture and Land Stewardship

Temperatures through the last week of July were seasonal across much of the state with sections of eastern Iowa reporting slightly warmer conditions. Iowa’s average temperature was 73.0 degrees, 0.4 degree above normal. Unseasonably dry conditions continued over a majority of Iowa, though parts of the state’s southwestern corner reported rainfall totals of up to two inches above normal. In the opposite corner of Iowa, departures of more than an inch below normal were observed.

An upper-level disturbance continued to move south through Sunday (26th) afternoon, bringing light to moderate rainfall to much of Iowa. Following closely behind, a sluggish cold front re-fired evening thunderstorms in southern Iowa. Showers and thunderstorms remained over southern Iowa into Monday (27th) morning as temperatures behind the front dipped into the upper 50s and low 60s across Iowa’s northern third. Rain totals for the previous 24 hours showed that the highest amounts occurred in southern Iowa with over 40 stations reporting an inch or more. Many stations in the southwest reported over two inches with a gauge in Osceola (Clarke County) observing 3.01 inches; the statewide average rainfall was 0.41 inch. As skies cleared though the afternoon, highs reached into the low to mid 80s with a light northerly wind. With high pressure controlling the pattern, clear skies overnight into Tuesday (28th) dropped morning temperatures into the low to mid 60s; some upper 50s were also reported, up to four degrees below normal. Daytime highs rebounded into the mid to upper 80s with sunny skies and southerly winds. Isolated showers formed in northern Iowa with some stronger storms leaving higher amounts in the state’s northwest corner. Rainfall ranged from a trace at a handful of stations in north-central Iowa to 1.15 inches at Akron (Plymouth County).

A boundary set up over northern Iowa separated cloudy skies and northerly winds from clear conditions and southerly winds across southern Iowa into Wednesday (29th) morning; temperatures were generally in the 60s. As the boundary transitioned to a warm front, partly cloudy conditions pushed farther south as morning lows remained in the upper 60s and low 70s. As the day progressed, showers and storms pushed into southwest Iowa. With muggy conditions and temperatures in the 80s, additional thunderstorms formed along the warm front during the afternoon. Some of these storms persisted along a concentrated east-west swath across the middle of Iowa. A low pressure center in northern Missouri spun additional bands of scattered thunderstorms into eastern Iowa though Thursday (30th). Morning rain totals along the Iowa-Nebraska border were between 0.30 inch to around one inch with locally heavier totals. There was also another pocket of heavier rain in east-central Iowa where Marengo (Iowa County) reported 2.44 inches. Gusty northerly winds and cloudy skies kept afternoon highs in the upper 70s and low 80s. A pocket of thundershowers worked across southeastern Iowa during the evening hours and pushed southwest before dissipating; rainfall was generally under a few tenths of an inch. Friday (31st) was another pleasant day with highs similar to Thursday and lower relative humidity. The average statewide high was 82 degrees, two degrees below normal. High pressure lent to quiet conditions into Saturday (1st) though clouds were on the increase in western Iowa as scattered thundershowers pushed into the northwest quadrant. Additional showers popped up in northern Iowa into Sunday (2nd) morning. The state’s western one-third picked up measurable totals on the order of few tenths to near an inch. Low temperatures were in the mid 50s to mid 60s with departures of up to 10 degrees below normal at some stations.

Weekly precipitation totals ranged from no accumulation at stations in northern Iowa to 3.22 inches in Oakland (Pottawattamie County). The statewide weekly average precipitation was 0.62 inch while the normal is 0.94 inch. Multiple stations in eastern Iowa reported the week’s high temperature of 94 degrees on the 26th, on average 10 degrees above normal. Webster City (Hamilton County) reported the week’s low temperature of 51 degrees on the 1st, 10 degrees below normal.