Over the past few decades the progressive automation of the Canadian climate network has been undertaken by each of five National Regions (Pacific and Yukon, Prairie and Northern, Ontario, Quebec, Atlantic). As a consequence the national climate network is populated with a variety of different sensors installed in a variety of configurations. Although the performance specifications of these sensors may be provided by individual manufacturers, no nationwide field evaluations have been undertaken by the Meteorological Service of Canada. A comparison and field evaluation of the majority of sensor models currently in use in the Canadian climate network would provide: 1) An accurate assessment of the measurement uncertainty of individual parameters in the Canadian climate archive; 2) The ability to accurately assess the current level of performance when specifying future procurement requirements for the network. This paper will describe the experimental design for a field evaluation of temperature and humidity “sensors in use” in the Canadian climate network. Some preliminary results will be presented.