Most cooling towels claim they will keep cooling for between two and five hours. This depends heavily upon air temperature and local weather conditions. Towels will dry more quickly in environments where the humidity is low and temperature is high. Conversely, in hot, muggy climates, some may stay damp so long that they warm with your body heat. Either issue is a quick fix, though, as long as you have access to water. If your towel is too dry or has become too warm, simply saturate it with cold water, wring it, and snap it to start the process over again.