The application of Laser Induced Fluorescence (LIF) for temperature measurements in water using a Nd:YAG laser is investigated. A natural convection problem is used to test the applicability of LIF in the temperature range of 20–60°C. The measured temperature field is compared with numerical results and the influences of shadowgraph effects on the measured temperature field are investigated. An accuracy of 1.7°C is attained if shadowgraph effects can be neglected. This only holds if correction for photobleaching and variation of laser power output is applied.