The incidence and severity of many diseases of cattle, particularly the endemic enteric and respiratory diseases, appear from clinical impression or epidemiological survey to be associated with particular types of weather. Infectious diseases of cattle (excluding parasitic ones) for which there appears to be a real association between climate, weather and disease are reviewed. Effects of weather on survival and spread of microorganisms, local resistance to infection and systemic resistance to disease are discussed. Factors such as cold, heat, relative humidity and air pollution are considered with particular reference to the aetiology of respiratory diseases.