4 Inch Soil Temperature Maps
 
County temperatures derived from ISU observations (www.pals.iastate.edu/campbell) by grid-interpolation.
Risk of nitrogen loss is reduced when soil temperatures are continuously below 50F.

Dates during the past few years when the soil temperature cooled to below 50F for various spots in Iowa:

   
  • 2008-- Statewide soil temperature cooled to below 50F on November 7.
 
  • 2007-- Soils North of a line from Council Bluffs to Waterloo and then directly East cooled to below 50F on November 1st and statewide on November 13th.
 
  • 2006-- Soils in the northwest 10 counties of Iowa cooled to below 50F on November 9th and state wide on November 29th.
 
  • 2005--Soils in the northwest 9 counties of Iowa cooled to below 50F on October 30 and statewide on November 12th.
 
  • 2004--State-wide soil temperature cooled to below 50F on Nov. 21st.
 
  • 2003--Iowa soils cooled to below 50F by Oct., 28th.  However, a warming impacted the areas south of Highway 20.  Soils south of Hwy. 20 did not remain consistantly below 50F until Nov. 21st.
  • 2002--Entire state soil temperature below 50F: October 22
  • October 13 Nashua, Ames
  • October 15 Sutherland
  • October 16 Castana
  • October 17 Crawfordsville
  • October 19 Lewis
  • October 22 Chariton
  • 2001--November 21 average--soil temperature fell below 50F:
  • November 18 in NW Iowa
  • November 26 all other locations except the Burlington area
  • November 30 Burlington area
  • 2000--November 3 (Kanawha, Nashua, and Ames)
E. Taylor, Climatologist