The present application discloses systems and methods for detecting a frost condition using a water temperatures sensor on an autonomous vehicle. The water temperature sensor includes a wind tunnel tube forming a hollow path for an airflow. The system further includes a fluid valve coupled to a fluid reservoir to dispense a fluid into the airflow of the hollow path. The water temperature further includes wet-bulb temperature sensor affixed to a vent coupled to a distal end of the wind tunnel tube. The wet-bulb temperature sensor configured to capture sensor data indicating a frost condition.