Falling prices may be a 'warning sign' of a recession. [=may indicate that a recession is coming]
There were storm 'warnings' [=warnings that a storm was approaching] issued for the area.
I'm giving you 'fair warning' that you had better not discuss politics at dinner tonight.
(..) Just like you, apparently. The day starts at a.m. sharp with the nurse. He needs to hours of care every morning. I'm warning you. Most people give up after a week. They come and go pretty fast. Well... I like the furniture, the music, it's cool and all... (..)2011 The Intouchables