A frost or snowflake symbol commonly draws attention to low outside temperatures. It does not confirm that a particular road is icy, and the absence of the symbol does not guarantee good traction.
For Sioux Falls driving, use actual conditions to set your speed and following distance. Check the owner's manual for the temperature range that activates your indicator. If the outside-temperature display seems consistently inaccurate, mention that separately when contacting 12th Street Auto Care Center.