Why not: I like today's sunny weather?
Probably because the arabic sentence was directly translated from English to arabic so it comes off as awkward
Yes, it is because, highly possible, contributors try to translate the Arabic sentence literally as much as contributors can -- so it'll not make the lessons more complicated.
It happens in other language courses also.
This is a weird phrase to utter in Arabic.
A better one could be :
أعجبني طقسُ اليومَ المشمسُ
Another weird sentence, it would possibly mean that you like a different weather every other day lol
I do like sunny weather today
It's correct translation also.
You silly owel.
أحبُّ الطقسَ المشمسَ اليومَ.