The Jet Stream complex over the Pacific is comprised of multiple Jet Streams which form, intensify and weaken in differing manner depending upon the synoptic situation and area. Regional differences within the Pacific are discussed. The axis of seasonal “strong” winds is determined and compared to the mean position of the principal baroclinic zone. Multiple Jet Stream systems are related to multiple baroclinic zones and characteristic temperature ranges of these zones are delineated and compared to values given for North America. Specific thermal and contour height ranges at the 500 mb level can be identified with each of the multiple Jet Stream systems. The distribution and incidence of “strong” wind velocities at the 500 mb level with certain 500 mb contour heights and temperatures is demonstrated for selected stations in the Pacific. Use of these thermal-contour height ranges as an aid in identification,location and forecasting of the Jet Stream complex is emphasized.