Extensive winterkill of golf greens is a major problem in northern climates. In this study, the efficiency of several protective covering materials used to shelter Poa annua golf greens from winter damages was evaluated over 2 years. The bioclimatological environment under these protective covers was studied at crown level and at 5, 10, and 20 cm under the ground Treatments (permeable and impermeable covers, curled wood Excelsior mat, straw mulch protected by an impermeable cover, geotextile material with an impermeable cover, and air space under an impermeable cover) were compared to a control treatment without protection. Results indicate that temperature profile was strongly influenced by both winter protection covers and snow depth Temperatures at crown level were stable and just below 0C under plots covered with a significant amount of snow. However, temperatures varied considerably, when snow cover was <15 cm. Snow thermal conductivity was increased by periods of rain during the winter. Impermeable covers minimized the negative effect of this change in the insulation properties of the snow cover by limiting temperature fluctuations at the crown level. Temperature profiles under permeable covers were similar to profiles observed on control plots. Temperature profiles were comparable for 5 and 10 cm air space treatments and were not significantly different when compared to impermeable covers spread directly on the turf. Straw with an impermeable cover and Excelsior mats maintained crown level temperatures at >0C and the incidence of disease was higher under these highly insulative materials.