Temperature is often an important determinant of species presence and activity patterns, but observations of temperature at fine resolution and broad extents—scales relevant to individual organisms—are rare. We analyzed how biotic and abiotic variables influence ground surface temperature (GST) using high-resolution thermal data for a 1900-ha area of forest and field near Wasaga Beach, Ontario, Canada. Temperature was recorded at 2-h intervals from May to October, 2004 and 2005, from data loggers approximately 300 m apart. At the same sites, we recorded overstory and understory vegetation, elevation, and distances to the nearest road and urban infrastructure. Correspondence Analysis (CA) indicated that thermal conditions varied most strongly seasonally and diurnally. Canonical Correspondence Analysis (CCA) pinpointed which biotic and abiotic variables were related to surface temperature. Canopy cover and leaf litter cover were positively related to cool sites during both cool and warm periods. Sites close to urban areas and roads were warmer than those further away from these features. As thermally variable environments affect the physiology, behaviour, and ecology of ectothermic species, determination of variables that affect GST provides a more comprehensive depiction of habitat for these species.