Polish (and I think most Slavic languages) are broken in the Southern Hemisphere. The words for "north" and "south" are identical to the words for "midnight" and "noon" respectively. The idea is that the direction is where the sun is at that time.
-
You probably thought that because of english 'middle'. Sounds similar. But midi is "au milieu du jour". Di from latin Dies (PT Dia, ES Dias). Also seen in other places, like Diurne or week days Lundi, Mardi, Mercredi,...
