I would match the water temp as closely as possible... Even though its a small amount it will still make Cold spots in the tank.. As a rule of thumb you should always match pH, Temp, And Salinity as closely as possible when doing water changes.. Remember that some SW
species such as inverts, corals, anemones, and some fish are Extremely sensitive to even small changes in water parameters... This would be the reason that people think of SW
being a "Hard" hobby to keep as the fish can easily become stressed and die over very minimal changes in the environment.. Where as I have had FW
fish and it just about takes a Knife to kill them things...