The climate of a region can be considered as a natural tourism attraction. Due to having favorable natural conditions and specific cultural features, Roudsar city in the east of Gilan province has a high potential for tourism. This study is aimed at assessing the conditions of climatic comfort and determining the optimal tourism time in this city using the stress index. For this purpose, the average monthly temperature, relative humidity and wind speed of weather stations of Rudsar, Haratbar, Kakroud, Spely and Shalman were used for a 10-year period (2000-2009). The results show that bio-climate comfort conditions in area under investigation, in the months of April, May, June, September, October, November and December are good for tourism activities and, with proper planning, we hope that authorities can provide favorable conditions for tourism, recreation and leisure time activities, which can have an influential role in economic development, income raise and employment levels of the area.