The induced static pressures due to a highly underexpanded sonic jet ejecting normally from a flat plate into a subsonic crosswind have been investigated. These pressure data have been recorded on the flat plate for a range of nominal jet-to-free-stream dynamic-pressure ratios from 0 to 1000 at free-stream Mach numbers of 0.1, 0.2, 0.4, and 0.6. The static pressure data measured on the flat plate are presented and correlated based upon the Riemann shock geometry in the jet plume. This data correlation improves with increasing free-stream Mach number.