SSH has being proposed to be secure and almost impossible to decrypt (at least for a user-level as the cafe case you're proposing). So most answers would say "no, your login cannot be compromised".
But, recently, as many hackers have been used the SSH tunnels for bad purposes due to its security (as security devices and software may not be able to inspect and/or distinguish malicious or not-malicious ssh traffic); some firms have been developing new products that are able to decrypt and inspect SSH traffic. If, as a theoretical example, a bad actor is running that wifi, using a firewall that lets decrypt and inspect SSH connections, it can be used for a MitM attack (Man-in-the-Middle). Obviously (as @kaidentity remarked and i forgot to tell, thanks) this only would work if the client did not check the server's public key fingerprint.
Readable example: http://blog.checkpoint.com/2015/08/12/ssh-decryption-opens-door-to-very-old-security-vectors/