Sea temperature have a great impact on weather and climate around the world. For instance, every 3 to 6 years a swath of the Pacific Ocean along the equator warms by 2 to 3 °C. That warming is a sign of the El Niño, that changes rainfall around the globe and causing huge rainfalls in the southern part of United States, Indonesia, southern Asia and in Australia. On a smaller scale, sea temperature impact on the development of tropical cyclones, that get energy from warm oceans.
Measuring Sea temperature:
There are a lot of different ways for measuring sea temperatures. Different aproaches can give different results. The oldest technique for measuring sea temperature was dipping a classic thermometer into a water, which was manually drawn from the surface. Next technique and the first automated was measuring water temperature in the intake port of ships. This is also not very consistent way of measuring, because the depth of the water wasn't alway the same. Most accurate measurments came from fixed buoys where the depth is cca. 1 meter. These measurements of sea temperature can be then distributed via satellites. New aproach for measuring sea temperature is measuring with satellite. This aproach is used since 1980s. Satellite measurements are in most cases more accurate and far more consistent.