Hibiscus Plants can usually survive winter temperatures of 50 F or above but if the temperature in the winter falls below 50 F or at the freezing temperature or below freezing temperatures then the Hibiscus Plants usually will freeze and die.
If your winters get below 50 F you should keep the Hibiscus Plants inside to prevent them from freezing and then place them outdoors during the spring when there's no threat of frost or freezing temperatures.
Hibiscus Plants will die if put in freezing weather conditions so always keep the Hibiscus Plants inside during cold winter weather.