During the past decade marine heat waves (MHW) have dramatically increased their presence, aerial coverage, and duration poleward of the deep tropics in both hemispheres. The influence on climate is dramatic and warrants application of a 10-year optimum climate normal (OCN) both to generating seasonal forecasts and explaining climate regime observations on an annual, seasonal, and monthly basis. In February 2024, MHW’s occupied 38% of the global oceans ranking 5th during all months since 1991 according to NOAA.