Atmospheric blocking is an important dynamic phenomenon in middle latitudes with potential to cause severe weather events. This study aims to investigate the climatology of wintertime blocking in the Northern Hemisphere. The JRA55 reanalysis data for the period 1959–2020 was used with potential vorticity–potential temperature framework to carry out the climatological analysis of blocking occurrence by using a blocking index based on Rossby wave breaking. Results showed that the Euro-Atlantic and West-Asian sectors are, respectively, the main places for the formation of blocking in the Northern Hemisphere, while the west coast of North America, and Central Pacific are next in rank. In addition, the trend analysis of the time series of blocking episodes in the two sectors of West-Asia and the west coast of North America (Euro–Atlantic sector) showed that the frequency of blocking occurrence has a significant (non-significant) increasing (decreasing) trend.