Snow is forecast across portions of Iowa between late today (Wednesday) and early Friday of this week, with accumulating snow possible especially in the north and west. Snowfall in Iowa in May is unusual, but far from unprecedented. According to data from the State
Climatologist office snow has fallen in May in 59 of the last 125 years, or 47% of the time, but it has only occurred in five of the last 20 years. Most of the events were characterized by isolated flurries with trace amounts at only a couple of reporting stations.
That most recently occurred in 2011 when a trace of snow was reported May 1 at Forest City and May 3 at Lansing.Widespread and measurable snowfall events are more unusual in May. The last measurable May snow reported in Iowa fell on May 1-2, 2005 with traces across about the northern third of the state, 0.1” at Stanley and 0.3” at Cresco. Similar events occurred on May 1, 1997 and on May 5-6, 1989.
Snowfall events producing multiple inches of accumulation are exceedingly rare in Iowa in May, having occurred in only ten years according to the research of the author, Jim Lee. He says most of these events occurred in the late 1800s and the first half of the 20th century, in fact no station has reported an inch or more of snowfall in Iowa in May since 1967.
Here is a list of the five events producing the highest May snowfall accumulations on record in Iowa:
In 1882, snow fell on May 12 (across southeastern Iowa, with about an inch at Iowa City) and then again on May 23. On the latter date about the southeastern quarter of Iowa received snowfall, with around half an inch at Des Moines and up to 4-6” at Washington.
In 1907, spring was very cold and backward at least partially due to the large eruption of the volcano Ksudach in eastern Russia. Snow fell across all of Iowa (and the Midwest) on May 3, with amounts ranging up to 1.2” at Des Moines and 1.5” at Atlantic and Corning.
Another statewide snow fell on May 15 that was light in most areas but amounted to 5” at Rock Rapids.
In 1945, snow fell across about the northwestern half of Iowa on May 9-10 with most of the area reporting measurable snowfall. Amounts ranged up to an amazing 8” at Denison.
In 1947, one of the most remarkable weather events in Iowa history occurred when snow fell across most of the state on May 28, with measurable snow across the north and west ranging up to an incredible 10” at Le Mars. This is the latest spring snowfall on record in Iowa and also the highest amount ever recorded in the month of May.
In 1967, snow fell across about the southern half of Iowa on May 3, with amounts ranging up to an amazing 8” at Glenwood.