Wisconsin-Minnesota degree day calculator

WI-MN Cooperative Extension Agricultural Weather Page

Degree days are a mathematical way of measuring the amount of heat available above a threshold temperature on a particular day. The number of degree days accumulated over some period of time is often related to the phenological development of plants and insects, and so can be used to estimate when pests will be at a life stage vulnerable to control. The base, or lower threshold temperature is that below which the organism does not grow or develop. The cap, or upper threshold is the maximum temperature at which organismal development occurs. Some specific examples can be found at our European Corn Borer, Alfalfa weevil, and Colorado Potato Beetle web pages.

A general introduction to using degree day calculations can be found on the UW IPCM website .

Select Desired Climate Data

1) First, please select the location for the degree day data you wish to calculate:

Map of area between latitude 42 and 50 degrees north, longitude 86 to 98 degrees west. (north) Latitude (west) Longitude

2) Next, please choose the degree day calculation parameters required:

Note: These parameters are usually specific for a particular crop and pest. Make sure you are using the right ones for your particular situation. Some values for common pests in our area are listed below.

Biofix (begin) date:

Year Month Day

End date:

Year Month Day

Degree day method:
Lower threshold temperature (Degrees F):
Upper threshold temperature (Degrees F):

Pest Method Base Temp Upper Temp Biofix

Apple Scab Simple 32F None Bud break

Alfalfa Weevil (DD map) Sine 48F 86F January 1

Black Cutworm Sine 50.7F 86.0F

Cabbage Maggot Simple 43F None January 1

Colorado Potato Beetle Simple 52F None When eggs are first scouted

Common Asparagus Beetle Simple 50F None January 1

Corn plant development (DD Map) Modified 50F 86F Emergence

Corn Rootworm Adults Simple 50F None January 1

Cranberry plant development (DD Map) Modified 45F 86F Ice off

European Corn Borer (DD Map)
(Sweet corn, Field corn) Modified 50F 86F January 1

Fleabeetles
(Beet, Cole crops, Potato) Simple 50F None January 1

Imported Cabbageworm Simple 50F None January 1

Onion Maggot Simple 40F None January 1

Squash Vine Borer Simple 50F None January 1

Stalk Borer (DD Map)
(Sweet Corn, Field Corn, Potato, Snap Bean) Sine 41F 86F January 1

Tree and shrub pests (DD Map) Modified 50F 86F January 1

3) Data output format:

Display date as year and day-of-year (default is year-month-day)

Seven day summary page.
As text, for selected time period, ready for downloading.

4) Finally, click the "Submit" button to obtain your results:

For further information on this page,
contact Bill Bland at the Dept. of Soil Science, Univ. of Wisconsin-Madison
Bill Bland, wlbland@facstaff.wisc.edu