Average sea surface temperature during spring, as represented by data for April, is illustrated for the four major shelf regions. These regional indices present a coherent depiction of SST in the ecosystem. The time series minima in spring SST occurred during 1992 and the maxima occurred during 2000. Since then, there has been a general trend of decreasing spring SSTs in all four regions. The variability in spring indices decreases with latitude with the range in mean SST being nearly 6°C in the Mid-Atlantic Bight and decreasing to less than 2.5°C in the Gulf of Maine.