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Transforming Climate Variability and
Change Information for Cereal Crop Producers


U2U Decision Support Tools - Corn GDD

Welcome to the Corn Growing Degree Day (GDD) decision support tool.

This tool puts current conditions into a 30-year historical perspective and offers trend projections (based on climatology) through the end of the calendar year. GDD projections, combined with analysis of historical analog data, can help you make decisions about:
  • Climate Risks– Identify the likelihood of early and late frosts/freezes.
  • Activity Planning – Consider corn hybrid estimated physiological maturity requirements, along with GDD projections when making seed purchasing and other growing season decisions.
  • Marketing – Look at historical and projected GDD when considering forward pricing and crop insurance purchases.

While this tool is not meant to be a crystal ball, data and information derived from the tool can be used to make helpful inferences about current conditions, especially when combined with personal experience and localized knowledge. Please note that data is currently limited to states within the U2U project area plus Kentucky & Tennessee.

To get started, click on any location within the gray area of the map. Use the zoom function for a more accurate selection.

Tool Tips:
  • Use the layer icon in the upper right hand corner of the map to control your viewing options.
  • Tested with browsers: Internet Explorer 11 & later; FireFox 27.0 & later; Chrome 33.0 & later; Safari 5.1.10 & later.

This tab allows you to put corn (86/50) GDD progress into a 30-year historical perspective. Customize your data:
  • Choose your GDD start date, freeze temperature threshold and corn maturity rating
  • Add any year between 1981-2013 for comparison
  • Adjust the spread of historical GDD and temperature data visible on the graph
  • Add or remove silking, black layer and freeze dates for a comprehensive growing cycle snapshot

GDD Start:
GDD Comparison Year:
Corn Maturity Days:
Freeze Temperature (°F):
Percentile Range:
Current Day:

Tool Tips:
  • Click the blue information icons for additional details.
  • Print this chart or export it in a variety of formats using the Chart Options feature.
  • Add or remove visual elements by clicking on their corresponding legend icons.
  • Zoom in by clicking above or below the plotted data and dragging your cursor to the right or left. Use "Reset zoom" button in upper right of graph to zoom out.

This tab allows you to put GDD progress into 30-year historical perspective. Customize your data:

GDD Start:
GDD Comparison Year:
Corn Maturity Days:
Freeze Temperature (°F):
Percentile Range:
Current Day:

User Input Summary

Location (lat, long): Tippecanoe Co., IN

Location (county, state): Tippecanoe Co., IN

Starting Date: Tippecanoe Co., IN

Today's Date: Tippecanoe Co., IN

Relative Maturity Rating of Crop: Tippecanoe Co., IN

Growing Degree Days to Silking: Tippecanoe Co., IN

Growing Degree Days to Black Layer: Tippecanoe Co., IN

Growing Degree Days Results       30-Year Average (1981 - 2010)         

This YearAverageEarliest 5 PercentLatest 5 Percent

Growing Degree Day Accumulation997105010201040

(September 30 - September 30)

Silking Date (Estimated)September 30September 30September 30September 30

Black Layer Date (Estimated)September 30September 30September 30September 30

U2U Growing Degree Day Tool Information

Select the links below to display or collapse the blocks of information.

Map Tab

  • One selects a location within the U2U area (grayed area) on the map to define the location to use for a Growing Degree Day (GDD) analysis. If one selects a location outside of this area a message is presented indicating that no data is available for this location.

  • Some notes on making selections:

    • If one has made a selection and the popup information box is displayed, one cannot select a new location within a box bounded by the top (or bottom) of the box and the bottom (or top) of the pointer. If you need to make a selection within that area, close the information popup first.

    • When one is satisfied with the location, select “Create GDD Graph” within the balloon window to create a GDD graph. [This selection causes the data for that location to be read from files containing the 30-year (1981-2010) average, 30-year (1981-2010) median, comparison years (1981-2012) GDDs and current year (2013) GDDs. Also the temperature threshold information to be used for the graph are read.]

  • The buttons in the upper left allow one to zoom in (+) and out (-) of the image. The “World” icon between the + and – allows one to zoom to the default area which includes the entire U2U area.
  • The arrow buttons above the zoom buttons allow one to scroll around the image. Note that one is not allowed to scroll around to areas that are very far outside of the U2U area.

  • The + in the upper right of the image is a pop-down menu that allows one the ability to select different maps for the background and the ability to turn the U2U State and County overlays off and on. The + changes to a – when the menu is being display. Selecting the – will cause this menu to be hidden.

  • The location of the cursor in latitude-longitude units are displayed in the lower left of the map.

  • Location aware devices: If one runs this tool on a location aware device such as a smart phone or tablet and the user agrees to allow the location to be used, a popup box will automatically appear at the location of the user. The map is zoomed in to an approximately state sized area. Also note that the zoom and pan buttons are not displayed.

Graph Tab

Data Tab

Information Tab

Animations Tab

Details behind the GDD Data (pdf file will open in separate browser tab)

U2U Corn Growing Degree Day Animations

The following time-lapse animations are visual representations of annual GDD accumulations. Click the play button to start chosen animation.

The following is an animation for 2013.

The following is an animation for 2012.

The following is an animation for 2002.


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Copyright 2013

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