In order to investigate if the Citrus disease Tristeza could be caused by a change in the rainfall, its distribution or in air humidity a study of these factors was made based on data obtained from 1890 to 1945 at Campinas, São Paulo, Brazil. A large variation in the data was found but no tendency could be noticed as to increase or decrease of any of factors analysed. This does not support the general belief that climate has been changing and the disease Tristeza cannot be assumed to be caused by change of any of the factors analysed.