Description: This research was conducted in order to define the effect of temperature-humidity index, cold stress index and length of dry period on birth weight of calves. In this study, pedigree records of 551 Jersey calves in breeding cow pedigree which were born between 2000 and 2004 in Samsun Karakoy Agriculture Enterprise and temperature humidity index together with cold stress index that were calculated by using climatic data obtained from General Directorate of Meteorology were used. These data were classified as three groups for dry period length, temperature-humidity index, cold stress index