Five years of winter survival data for winter wheat (Triticum aestivum L.) were collected at a site on the Central Experimental Farm at Ottawa, ON (45° 23' N, 75° 43' W). The site was low lying and subject to frequent winter flooding and ice sheet formation. The objective of the study was to gain insight into factors which might affect winter survival. Two varieties of winter wheat were planted in September. Crop establishment was measured in late fall and the percentage survival was measured in April of the following year. We assumed the large spatial differences in survival were affected by spatial variation in environmental factors such as snow and ice depth, soil moisture and temperature. Hourly measurements of 0.05-m soil temperature were recorded throughout the fall, winter and spring. Fall and spring soil moisture were measured on the plot as well as snow and ice depth at selected times throughout the winter. Measurements were taken on a grid covering the plot in order to contribute to the explanation of spatial variation in survival. In addition, detailed measurements of elevation were taken on a grid. Meteorological data were available from the nearby weather site. Correlation and multiple regression analysis were used to relate year to year variation in survival with environmental factors. In years where winter flooding and ice sheet formation occurred, the spatial variation in winter survival was related to differences in elevation and the resulting surface drainage patterns. A model based on CERES for cold temperature survival showed that soil temperatures were never cold enough to reduce survival.