I did wondered the same that it is very stupid to not to include staple apps like Weather , calculator etc.
well Apple did provide Weather in iPad Mini n other ipad too maybe, but just not as detailed as in iPhones.
One can find weather of their location in CLOCK app , yes there in. world clock it shows the current weather of cities n places you have added in world clock tray it is very abrupt but its the only built in weather status ! Hope it works
Ciao ! Lol