Ablation is carried out by bringing a probe into contact with a target tissue. The probe has a plurality of temperature sensors and an ablation electrode on its distal portion. The temperature sensors are distributed circumferentially about the longitudinal axis such that the probe has an omnidirectional temperature sensitivity. After verifying that contact exists between the probe and the target tissue, and while applying energy through the ablation electrode data from the temperature sensors is repetitively recorded. Thereafter, responsively to detection of a drop in temperature with respect to the baseline temperature level, it is concluded that a loss of contact between the probe and the target tissue has occurred. The operator is thereupon alerted.