You got the good idea, but you just have to be careful to not make logical or verb tense mistakes.
Should probably be
思ったより上手くいった。-> It went better than expected.
思ったより上手くいっている。-> It is going better than expected.
Right now you are expressing present/future tense, which doesn't fit well with your thought in the past. You could say it like that though.
思っているより上手くいくでしょ。-> It's probably gonna go better than your are thinking.
As for talking about things like the weather, you might want to use words like 予定 instead of 思い. There is a certain nuance between what you think and what is planned.