Ocean currents affect the temperature in the following ways
Currents influence the climatic conditions of the regions in which they blow. The warm equatorial currents raise the temperature of the region in which they blow. Similarly, the cold currents lower the temperature of the places where they blow. For example, British Isles would have been extremely cold without the warm North Atlantic Drift. The hot climate of Peru is cooled by the cold Peru Current.
Also, Read Movements of Ocean Waters