Purpose Hypothermia is a key performance indicator (KPI) in U.S. Ambulatory Surgical Centres (ASC). This study assessed prevalence and risk factors for perioperative hypothermia in day-only laparoscopic cholecystectomy (DOLC) and compared results to U.S. ASC benchmarks. Methodology Retrospective analysis of 664 DOLC patients (2021–2024). During surgery, all patients received external forced-air warming, and cold, dry CO2 pneumoperitoneum. Tympanic membrane thermometers measured body temperature. Results Of 664 patients, 27.1% had postoperative hypothermia (<36°C). Lower BMI (<25kg/m², p=0.04; <20kg/m², p <0.009) significantly increased hypothermia risk, as did bilateral TAP block and preoperative hypothermia. Older age increased hypothermia risk by 1.4% per year, while each BMI increase of 1 kg/m² decreased risk by 5%. Intraoperative opioid administration was higher among normothermic patients (mean:49.7 oMEq, SD=23.0) compared to hypothermic patients (mean:44.3 oMEq, SD=20.4, p=0.009). Factors including sex, operative duration and surgery start-time did not impact temperature outcomes. Postoperative normothermia rates (72.9%) failed to meet U.S. ASC KPIs (>90% normothermia upon PACU admission). Same-day discharge rates did not differ between groups. Conclusion Perioperative hypothermia results from a combination of preoperative and intraoperative factors, including ambient temperature, general anaesthesia, loss of central thermoregulation, cold IV fluids, and CO2 pneumoperitoneum. Lower BMI and older age were significant risk factors. The hypothermia rate observed does not meet U.S. ASC quality benchmarks, highlighting areas for improvement in perioperative warming protocols and prevention of hypothermia during ambulatory