A frost or low-temperature indicator warns that outside temperatures have reached a range selected by the manufacturer. It is a reminder to consider slippery conditions, not a direct measurement of ice on the road.
Adjust your driving to what you can observe and leave appropriate space for stopping. Neither an illuminated snowflake nor its absence can establish the traction available at a particular location.
Check the manual for your vehicle's activation threshold. If the temperature display appears inaccurate or changes implausibly, describe the pattern when contacting Callagy Automotive & Smog.