Earth surface air temperature measurements are critical in meteorological observations. When taken for extended periods of time they provide essential indicator for climate change studies. Liquid in Glass (LiG) thermometers remain, in most parts of the Globe, the prevalent instrument to measure air temperature. The desire to eliminate, due to environmental reasons, the use of mercury, the need to increase automation and the increasing emphasis on maintaining the traceability of temperature measurements to has prompted efforts to investigate alternative methods for replacing the LiG.

Recent advances in measurement and communications technology allow for feasible alternatives to LiG thermometers. Industry provides battery and solar powered wireless sensors that are capable of meeting meteorological networks range and accuracy requirements. Through an internet interface, remotely received temperature measurements can be automatically disseminated and archived. The homogeneity of climate observations is one of the critical factors to be considered before a network-wide replacement program . The presentation will outline the alternatives being considered for the Canadian meteorological networks and the evaluation results to date.