The coldest temperature ever recorded at Glasgow, Montana, was -59°F on February 15, 1936. Arctic outbreaks with wind chills in the -30°F to -50°F range occur frequently during the winter months. These bitterly cold temperatures affect the agricultural community of northeast Montana as ranchers typically breed their livestock such that calving and lambing occur in February and March. During these critical weeks, ranchers require advanced warning of extreme cold to move susceptible livestock to shelter. Newborn animals (<24h old) are especially vulnerable to cold because they are not yet able to regulate their body temperature effectively (Stanko et al., 1991). For example, in one spring cold outbreak, a rancher in Big Sandy, Montana, lost 250 calves from his herd of 2000 head. This equated to a loss of approximately $110,000. Development of a warning system for dangerous events should allow producers to minimize mortality rates of newborn calves and lambs and the associated economic losses.

This study explores the feasibility of developing such a cold warning system for northeastern Montana by identifying weather conditions that result in livestock losses. This task must be completed successfully before an operational warning system can be developed and was accomplished by two means: 1. livestock producers in the region were surveyed to identify specific weather events that had caused losses in the area in the past; 2. a literature review identified studies that had been undertaken in other areas, or in climate chambers, to determine the effects of cold exposure on newborn animals. This study defines meteorological thresholds for which a cold warning would be called and sets the stage for the development of an operational warning system.