SSH: known host with dynamic address

I need to connect to a host with a dynamic IP address.
Every time its IP changes, SSH prompts me the fingerprint validation thing:
The authenticity of host '...' can't be established.
RSA key fingerprint is ....
Are you sure you want to continue connecting (yes/no)?



Would it be possible to pass SSH the host public key, so that:
SSH validates the host's authenticity automatically
The host key is not stored in the known_hosts file