So in general, regarding perishable foods like meat, most dairy, unshelled eggs and shell eggs (in the US) , cooked casseroles, and so on: if the food (or its perishable components) have been at room temperature for more than two hours, you should discard that food.
This directly effects how comfortable it will feel outside. Many times, relative humidity can be misleading. For example, a temperature of 30 and a dew point of 30 will give you a relative humidity of 100%, but a temperature of 80 and a dew point of 60 produces a relative humidity of 50%.
The air that is inside the ducts is much cooler than the air outside the ducts, and as the outside surface of the ducts is cooled, the humidity that is in the air outside of the ducts will start to form condensation.