If the temperature of the liquid changes, the S.G. may also change. Because temperature change will cause the liquid to expand or contract, depending on whether the temperature goes below or above the standard temperature.
The S.G. or Mass Density of most liquid is calculated at a Standard Temperature (60°F).
(The Effect of Temperature is that, as the temperature of the liquid increases, the liquid expands and gets lighter per volume. Consequently, the force per unit area will decrease. On the other hand, as the temperature of the liquid decreases, the liquid contracts and becomes heavier per volume and causes the force per unit area to increase.)---