The redbanded stink bug Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae) is an invasive stink bug species in the United States. First documented as a soybean pest in Louisiana in the year 2000, this species continues to spread in the Mid-South region of the United States. We designed laboratory and field studies to investigate supercooling points, lethal exposure time (LT), critical thermal minimum (CT_min), and winter mortality of this species. The mean supercooling points (SCP) ± SE of adult field collected P. guildinii ranged from −8.3 ± 0.2°C (highest) in March to −11.0 ± 0.2°C (lowest) in January. Significant differences in SCP occurred over the months and between sexes with significant interactions between month and sex. The CT_min was significantly different between adults and nymphs (third, fourth, and fifth instars combined). LT₅₀ and LT₉₀ were evaluated at subzero temperatures of 0°C, −2°C, and −5°C. There were significant differences in LT₅₀ and LT₉₀ among the temperature treatments. Winter survival significantly differed between the two study years and decreased with progression of winter months.