Besides just being hot outside, a number of weather factors including humidity, wind speed, nighttime temperatures and the duration of high temperatures contribute to the risk of heat stress in livestock. To help producers monitor those conditions and make management decisions during hot weather, University of Missouri environmental physiologist Don Spiers, PhD, developed a smartphone app called Thermal Aid. The 99-cent app tracks humidity and temperature through its GPS function. The cow’s respiration rate and other determining factors are submitted by the user with the help of tools available on the app. With the information available, the app provides the animal’s Temperature Humidity Index, a measure of how the animal is handling the heat. The tool advises the most effective intervention strategies when necessary. To download the app, search for “Thermal Aid” in the iTunes App Store, or to learn more about heat stress and the ThermalAid app, visit