Water temperature plays a crucial role in determining the distribution of aquatic organisms because most are ectothermic. The further spread of the invasive Asian clam Corbicula fluminea, a species causing enormous damage to water intake pipes and electric power plant cooling systems, has been assumed to be limited due to intolerance of very cold water, with a lower lethal temperature of about 2°C. In recent years, however, C. fluminea invaded most of the major rivers in Europe, including sections where the water temperature falls below 2°C for short periods during winter. Here we quantify the cold tolerance of C. fluminea in a controlled laboratory experiment. We show that C. fluminea has a greater cold tolerance than previously assumed. In water of 0°C, clam survival decreased from 100% to 17.5% with increasing exposure from 4 to 9 weeks. Considering actual water temperatures of rivers during winter and ongoing stream warming, we conclude that this invasive clam will establish in a wider range of waterbodies in Europe than previously predicted.