Weather Information for Your Farm: Making Good use of Your Computer

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 Valuable information on local weather conditions and patterns may be critical when determining farm management decisions. Evaluations about spraying (short term forecast for precipitation), crop, weed and pest development (heat accumulation and progress), crop choices (days for maturity) and farm record keeping can be addressed with good agroclimatic data.

There are many web locations where producers can obtain crop staging information. Montana State has a site with information on crop development using growing degree-days:
Using Growing Degree Days to Predict Plant Stages

Pest monitoring, pesticide applications or crop staging for harvest can involve Growing Degree day (GDD). Examples include head emergence of wheat for Orange Wheat Blossom Midge or predicting grasshopper emergence patterns on your farm. Using argentine canola information from the Montana site, GDD development can be used to predict crop stages.

Crop Stage
GDD Range
Emergence Cotyledons completely unfolded
152 to186
Two True leaves
282 to 324
Four leaves
411 to 463
Flowering with at least one open floret on 50% or more plants
582 to 666
Flowering 50% complete
759 to 852
Seed fill begins 10% of seeds have reached final size
972 to 1074
Maturity 10% of seed has changed color
1326 to1445
Swathing 40% of seed on main stem has changed color. Swathing recommended at this stage
1432 to1557

GDD°C listed above range from the low values, representing development under dry conditions, to the higher values representing cool/wet growing conditions.
Recently information involving the use of GDD has been suggested for planning swath grazing seeding dates for cereals.

Alberta Agriculture has an excellent site, found under the Weather and Climate, Agroclimatic Information Service, Agriculture and Climate Information Viewer

This site utilizes drop-down menus to produce maps for topics like Precipitation, Insects and Disease and even has an Agroclimatic Atlas with historic maps on growing season and frost-free days. Once you’re at this site I recommend the Weather Mapper option if you’re looking for growing degree-day information.
AAFRD also has an overall report on current Alberta conditions with precipitation and soil moisture maps:
Drought Reports for the Agricultural Region of Alberta

The federal site for Agriculture and Agri-Food Canada and the Prairie Farm Rehabilitation Administration (PFRA) has current condition maps that show growing season and “rolling” maps that show 7, 30, 60 and 90-day precipitation accumulation:
Drought Watch

Another source of great information, which I use repeatedly is FarmZone. Insect and crop development can be forecast with degree-day accumulations. Degree-day development is usually calculated on a “base” temperature, which varies between insects. In general, for a specific area you can compare (say Coronation) grasshopper hatch on your farm in 2003, 2004, 2005 vs 2006. The degree-day accumulation will be similar but the dates will vary. You can access this information at:

At this site choose the southern Alberta map section, then the Coronation section. Choose the Historic link in the green bar at the top, above current conditions. Through this method I have determined that 2006 is ahead of normal degree-day (heat) development units by about 40 degree-days or about 3-4 calendar days.
Crop development information can be found at:
Using Growing Degree Days to Predict Plant Stages

Short-term weather patterns affect planning, especially for spraying. Below is a link for weather forecasts over the next 72 hours or 3 days. The interesting component of this connection is a forecast of accumulated precipitation 0-72 hrs in the future, broken down into 6-12 hour segments:
National Weather Service

Click on the section of the map you are interested in, such as the 12-hour forecast, and it will enlarge. The geographic extent tends to deal primarily with the States, but covers most of the cropping zone in Alberta, excluding the Peace River Region.

With links to the above weather information sites you can answer many questions that are required to help in your farming decisions.

Prepared by Jim Broatch, Alberta Agriculture and Rural Development
For more information about the content of this document, contact the Ag-Info Centre.
This information published to the web on June 14, 2006.
Last Reviewed/Revised on November 27, 2013.