Zeeman interferometry, based on the two‐frequency Zeeman effect laser, can be used for simple, noncontact differential thermometry. The thermometry is differential in both space and time. Small (0.73 &mgr;l ) laser‐heated volumes were monitored with a Zeeman interferometer. Heating rates varied over six orders of magnitude from 180 &mgr;K/s to 330 K/s. Temporal resolution was 10 &mgr;s. Measured temperatures and measured rates of heating were compared with theory for slowly and rapidly heated samples, respectively.