Near-surface warming by either an increase in air temperature or radiation is believed to have a significant effect on dry-snow slab avalanche formation. However, it is unclear how and to which degree warming promotes instability. We have therefore quantified surface warming with respect to the contributing meteorological processes and investigated in situ the fracture behavior under conditions of surface warming. The relevant energy fluxes at the snow surface were partly measured and partly modeled with the snow cover model SNOWPACK and used to determine the energy input into the snowpack. To determine the effect of surface warming on slab properties, we derived the stiffness of snow layers from penetration resistance measurements on nine field days with the snow micro-penetrometer. On eight of these days propagation saw test experiments were performed at the same time and compared to the energy input at the snow surface. Moreover, the specific fracture energy of the weak layer, which in combination with the slab properties controls crack propagation propensity, was determined by means of finite element modeling. A reduction in stiffness by a factor of about 2 was observed in near-surface snow layers when the energy input at the surface exceeded 300 kJ m^-2. Meanwhile, weak layer properties showed no trend. Softer slabs were found to cause shorter cut lengths in propagation saw test experiments – suggesting that surface warming increases crack propagation propensity. For the first time the effect of surface warming on instability has been quantified. The results demonstrate a subtle influence of surface warming on snowpack stability. It is suggested that a pre-existing weakness and considerable energy input are required that surface warming may promote instability.