Some aspects relate to weather seal systems for forming water barriers and air barriers. Some air barriers include a sill portion, a frame portion, and a transition portion extending between the sill and frame portions, where the transition portion extends inwardly and downwardly from the frame portion of the air barrier, toward an interior side of an associated door assembly, to the sill portion of the air barrier. The transition portion optionally provides a buffer zone, or transition zone of air at a greater spacing from the water barrier. In some embodiments, the transition zone is equilibrated to external pressures and supplies substantially dry air to air leaks in the air barrier.