Synonyms for warn:
cautionary, monition, warn off, give notice, admonitory, hellfire, fire and brimstone, warn away, scaremonger, augury, admonishing, Prefigurement, prepare, Lowery, Unhospitable, apocalyptic, awaken to, alarum, apocalyptical.
dire, tip off, remind, threat, malign, ominous, intimidation, alarmist, sinister, uninviting, tocsin, warning, omen, admonishment, monitory, prognostication, baleful, portent, presage, baneful, direful.
prompt, tip off.
read the riot act to.