The Latin (Roman) word for "you" is "tu"... Reference the question of Julius Caesar in the Shakespearean play of the same name --- "Et tu, Brute ?" .... translated as "Even you, Brutus?" after Julius...
There is no single word for sunny day. You would use dies, which means day and apricus which means sunny. So sunny day in Latin would be dies apricus, the adjective folowing the noun.