For a person:
* As cold as a winter's night: This emphasizes the emotional coldness of the person.
* Like a snake in the grass: This implies a deceptive and dangerous nature.
* As sharp as a knife: This suggests a person who is quick to anger and easily offended.
* Like a raging storm: This highlights the intense and destructive nature of the person's hostility.
For a place:
* As desolate as a barren wasteland: This conveys a sense of emptiness and danger.
* Like a battlefield after the war: This implies a sense of destruction and chaos.
* As forbidding as a dark cave: This suggests a sense of mystery and danger.
For an atmosphere:
* As thick as a fog: This describes a feeling of tension and uncertainty.
* Like a pressure cooker ready to burst: This emphasizes the intense and potentially dangerous nature of the atmosphere.
Ultimately, the best simile for "hostile" will depend on the specific situation and what you want to emphasize.