Introduction: In critically ill patients (e.g., trauma victims) prevention of hypothermia is an important goal. Infusion of warm fluids has been addressed in the hospital setting, but not in the air medical transport setting. Purpose: The purpose of this study was to test the efficacy of an intravenous (IV) fluid warming device that is well-suited for the air medical transport environment. Method: The warmer studied was used with IV fluid heated to approximately 38°C (100°F) and evaluated in environmental temperatures of −16°C (3°F), 2°C (36°F), and 22°C (72°F). The warmer group was compared to a control group of similarly treated IV fluids without a warming device. Temperatures were measured at baseline, 15, 30 and 60 minutes. Results: The 30- and 60-minute fluid temperatures were higher in the warmer than in the control group for all three environmental temperature settings. At 15 minutes, fluid temperatures were higher in the warmer group for the 2°C and −16°C, but not the 22°C, environments. There was no significant drop in temperature in the warmer group in the 22°C and 2°C settings, but a decrease was noted in the −16°C environment. There was a significant drop in the control group at all temperatures tested. Conclusion: The IV fluid warmer tested effectively maintains the temperature of warmed IV fluids in temperatures above 2°C. At −16°C there was significant heat loss, but the loss was significantly less when compared to the control group.