General Summary.   April temperatures averaged 46.4º or 2.1º below normal while precipitation totaled 5.93 inches or 2.60 inches above normal.   This ranks as the 31st coldest and 2nd wettest April among 136 years of state records.   The only wetter April was recorded in 1999 with 6.25 inches of precipitation.   The last colder April was in 1997.

Temperature.   The first two weeks of the month were persistently cool.   Cresco and Elkader recorded the month’s lowest temperatures with 17º readings on the morning of the 2nd.   The temperature failed to reach 70º anywhere in the state until the 15th when Sioux City climbed to 78º.   A period of warm weather prevailed from the 19th through the 24th.   Temperatures reached 80º at Keosauqua on the 21st; at Keosauqua and Donnellson on the 22nd and again at Little Sioux on the 23rd.    Much colder weather returned for most of the rest of the month.   A freeze affected nearly all of the state on the morning of the 29th with Mason City the cold spot at 22º.   Sibley also reached 22º on the previous morning.   Warmer weather returned for the final day of the month with Glenwood and Shenandoah reaching 80º.   The temperature has failed to exceed 80º by the end of April somewhere in Iowa only three times in the 119 years that daily maximum temperature data are readily available statewide.   Those other years were 1993 (first 80+ day on May 5); 1973 (May 8) and 1944 (May 1).   The first four months of the year have averaged 3.7º colder than normal and mark the coldest start to the year in Iowa since 1982 (but only 21st coldest among 136 years of records).

Heating Degree Day Totals.   Home heating requirements, as estimated by heating degree day totals, averaged 1% less than last April and 11% more than normal.    Degree day totals for the season (since July 1, 2007) are running 8% more than last year at this time and 4% more than normal.

Precipitation.   The big weather news of the month was precipitation.   Rainfall was frequent during the month with three storm systems each dropping an average of over an inch of rain statewide on the 10th-11th, 17th-18th and 23rd-25th.   Heaviest rains with each of these storms was centered on central and northeast Iowa.   Major flooding followed the final, and largest, storm of the series.   Monthly precipitation totals varied from 1.90 inches at Sioux Center to 11.98 inches at Fayette.   Record maximum April precipitation totals were recorded at several locations including:

City                 Apr 2008 Total            Old April Record           Length of Record
Fayette                        11.98               8.02 inches in 1909                 119 years
Grundy Center           11.75               8.02 inches in 1991                 117 years
Waukon                      11.07               8.55 inches in 1981                   86 years
Waterloo                     10.79               8.53 inches in 1991                 126 years
Eldora                         10.25               7.22 inches in 1976                   66 years

These totals fell just shy of the April single-station record of 12.52 inches set at Strawberry Point in 1951.   The frequent rainfall allowed only 3% of the state’s corn to be planted by April 27.  This slow planting pace is similar to what was recorded in 1998 and 1999.   The 2007-2008 snowfall season slowly came to a close during April.  A few areas saw accumulations of 1 to 3 inches on the 3rd and 8th with a dusting in northern areas as late as the 28th.   The preliminary statewide average snowfall for the season stands at 44.7 inches, 12.3 inches greater than normal.   This was the snowiest season since 2000-2001 and ties for 10th snowiest winter among 121 years of records.   Several eastern Iowa locations reported record seasonal snow totals while some western areas actually had less snow than normal.   Preliminary seasonal totals varied from 15.4 inches at Logan to 85.0 inches at Dubuque Lock & Dam 11.

Severe Weather.   The season’s first severe weather outbreak came on the evening of the 10th with severe weather reported from 11 counties.   Other events came on the 22nd (9 counties) and 24th-25th (27 counties).

Outlook.   As expected the recent La Niña event is slowly starting to weaken.   In previous years with a similar La Niña trend the tendency has been for Iowa to transition into a drier weather pattern beginning in May.   Temperatures are most likely to be normal to cooler than normal over the next few months in the state.

Harry Hillaker, State Climatologist
Iowa Dept. of Agriculture & Land Stewardship
Wallace State Office Bldg.; Des Moines, IA  50319
Phone: (515) 281-8981