Introduction A new hot balloon system that registers balloon surface temperature (BST) during energy delivery is now available for clinical use in Japan. This study sought to investigate the utility of BST measurement for achievement of pulmonary vein isolation (PVI) by a single‐shot energy delivery strategy during hot balloon ablation (HBA). Methods We applied and tested the system in 30 consecutive patients undergoing HBA for paroxysmal or early‐persistent atrial fibrillation (AF). We also performed real‐time PV potential monitoring using a circular catheter. Results Acute PVI was achieved with single hot balloon shots in 88% (106/120) of the PVs. Real‐time BSTs and PV potentials were recorded in all cases. Mean BST at documentation of PVI was 49.4°C, and acute reconnections were observed in most cases (86%, 12/14) in which the single‐shot technique was ineffective. Time‐to‐isolation (TTI) (23.1 ± 8.7 s vs. 36.3 ± 9.3 s, p < .01) and median BST (59.9 ± 2.6°C vs. 55.7 ± 1.9°C, p < .01) differed significantly between cases in which PVI was achieved (vs. those in which PVI was not achieved). Multivariable analysis revealed strong association between both TTI and median BST and acute PVI. The best median BST cutoff value for achieving PVI with a single shot was >58.7°C (sensitivity 67.0%, specificity 100%). Conclusion Our data suggest that real‐time BST monitoring during energy applications is useful for predicting achievement of acute PVI by a single shot during HBA.