Provided by Justin Glisan, Ph.D., State Climatologist, Iowa Department of Agriculture and Land Stewardship
Above-average temperatures were observed across most of Iowa during the reporting period with a cool down from a cold frontal passage late in the week. The statewide average temperature was 72.7 degrees, 0.7 degrees above normal. Though most of the week was dry, a large-scale weather system brought widespread rainfall across Iowa with above-normal totals approaching two inches in drought-stricken northern Iowa; much of southern Iowa reported only a few tenths of an inch of rainfall.
Sunshine and southeasterly winds led to pleasant conditions on Sunday (15th) afternoon. Partly cloudy skies remained overnight into Monday (16th) morning as a dome of high pressure dominated the weather pattern over the Midwest, lending to quiet conditions. Afternoon temperatures ranged from the low to mid 80s west to upper 70s east. Starry skies and a light southerly wind held temperatures in the upper 50s and low 60s into Tuesday (17th) with some clouds streaming into central Iowa. Daytime temperatures were on the rise with increasing southerly winds and humidity; mid to upper 80s were observed in western Iowa while eastern Iowa reported temperatures three to five degrees cooler. Hazy skies were observed into Wednesday (18th) as wildfire smoke filtered into the region. Daytime highs rose into the 80s with a few 90 degree readings under partly cloudy skies. Morning lows reported at 7:00 am on Thursday (19th) were unseasonably warm, generally in the mid to upper 60s, up to nine degrees above normal. Dew point temperatures in the upper 60s and low 70s combined with afternoon highs in the upper 80s led to very muggy conditions into the evening hours.
Light showers formed in western Iowa early on Friday (20th) before dissipating during the late morning hours. Southwesterly winds picked up through the afternoon as a cold front approached the state front from the west. Muggy conditions continued, which helped fire stronger thunderstorms in northwestern Iowa as the boundary entered the state. Some storms turned severe with a brief tornado reported near Sibley (Osceola County), causing some damage to trees and outbuildings. As the front swept across the state, measurable rainfall was observed at a majority of stations with general totals of a few tenths of inch over the state’s northern half. Numerous stations in north-central Iowa reported above 0.50 inch with nearly 30 stations measuring an inch or more. Pocahontas (Pocahontas County) reported 2.15 inches while Webster City (Hamilton County) observed 2.92 inches. Behind the front, cooler and more pleasant conditions were experienced on Saturday (21st) with sunny skies and a light northerly wind. Temperatures remained in the mid 70s to low 80s during the daytime hours and dropped into the 50s overnight into Sunday (22nd) morning.
Weekly precipitation totals ranged from no accumulation at several southern Iowa stations to 3.26 inches at Webster City (Hamilton County). The statewide weekly average precipitation was 0.57 inch while the normal is 0.95 inch. Multiple stations observed the week’s high temperature of 92 degrees on the 20th, on average nine degrees above normal. Elkader (Clayton County) reported the week’s low temperature of 46 degrees on the 16th, 12 degrees below normal.