Technical Abstract: Cattle are adaptable to a wide range of climatic conditions, but can be severely challenged by sudden heat waves. Repeated hot, humid environments, with little air flow or cloud cover, are periods of concern, especially if conditions persist over a three-day period without significant nighttime relief. Early signs of animal discomfort include shade seeking, reluctance to leave the waterer, and increased respiration rate. Heat distress is generally marked by open mouth panting, little or no feed consumption, and excessive drooling. Most management practices to combat the effects require planning so that shade can be provided or water can be applied to wet animal hides, thus allowing evaporation to occur. Animal handling and routine treatment should be avoided if heat wave conditions are predicted.