Sea surface temperature, global map. The world's oceans are heated by sunlight, with variations in the surface temperature caused by varying latitude, the Earth's rotation, and axial tilt. Here, yellow and red colours show temperatures of 20 to 30 degrees Celsius in the equatorial regions. Colder temperatures further north and south are green and blue, from 10 to -2 degrees Celsius. Cooler regions are seen off the western coasts of Africa, South America and North America, where land-sea winds blow warm water away. The data used in this map is from the World Ocean Atlas 2005.