"Wela ʻo Kēhau."

Translation: Kēhau is hot.

[RonRGB]

Kēhau = A female given name, occasionally also given to men. Name of a gentle breeze on several Hawaiian islands.

[DCnF91]

Why is it wrong to say "it is hot in Kēhau "

[OhWowBro]

It's not a place. It's a person

[Kaz700065]

I guess I don't really know when to use 'o. Why couldn't one say "'O wela Kēhau" instead?