Pacific Ocean To determine the phase of ENSO, the most recent three-month sea surface temperature average for the area approximately to the southeast of Hawaii is computed, and if the region is more than above or below normal for that period, then an El Niño or La Niña is considered in progress. In the tropical western Pacific, the monsoon and the related wet season during the summer months contrast with dry winds in the winter which blow over the ocean from the Asian landmass. Worldwide, tropical cyclone activity peaks in late summer, when the difference between temperatures aloft and sea surface temperatures
Sea surface temperature measured. Away from the immediate sea surface, general temperature measurements are accompanied by a reference to the specific depth of measurement. This is because of significant differences encountered between measurements made at different depths, especially during the daytime when low wind speed and high sunshine conditions may lead to the formation of a warm layer at the ocean's surface and strong vertical temperature gradients (a diurnal thermocline). Sea surface temperature measurements are confined to the top portion of the ocean, known as the near-surface layer. SST was one of the first oceanographic variables to be measured. Benjamin Franklin suspended a