On the basis of measurement results of the lowest minimum temperature of air in given months, gathered from 9 IMGW meteorological stations over the period of 1956-2005, the time and spatial variability of this element on the Polish coast of the Baltic Sea was worked out. Absolutely the lowest daily air temperatures varied from about 2oC in August to about –30oC in February and January. Using the method of linear regression, the direction and the range of variability of minimum temperature throughout the whole country over the entire period of 50 years was analysed, showing the largest increase in temperature in February and in January which ranged from 2.3oC to 6.7oC per 50 years. The thermal classification according to individual months was carried out using the quantile method and that gave the grounds for the preparation of a calendar of changes of minimum daily air temperature. Since 1988 a distinct increase in temperature has been observed on the coast, particularly in winter and in early spring, and since 1997 – also in summer months. In the study the relationships between minimum daily temperature and mean monthly air temperature were analysed, obtaining statistically significant compounds, particularly in winter. A strong relationship was also observed between the mean monthly air temperature and the temperature amplitude (the difference between the highest maximum and the lowest minimum daily temperature in a given month), showing a statistically significant direction of changes – negative in winter and positive in summer.