An investigation of the polarization and temperature dependence of surface second-harmonic generation (SHG) at the air-water interface shows that the intensity of the SHG signal decreases over the range 20-70 degreesC. Accounting for the changes in the SHG polarization behaviour with temperature to extract the relative temperature dependence of chi (zzz) shows that it is similar to that obtained from simulation studies. The role of the interfacial refractive index in the interpretation of the SHG signals is addressed.