"What day is tomorrow?"
Translation:ʻO ka Pōʻahia ka lā ʻapōpō?
Sorry for asking all of these questions! When do you use: ʻO ka Pōʻahia vs O ka lā ʻehia?
Po'ahia refers to a day of the week, whereas la 'ehia is referring to a general date "the 3rd of March". I've found that several of the different languages I've studied really dig into the nuances of the concept of what English speakers are satisfied with summing up as "When is..."