YOU SAID:
nice weather isn't it?
INTO JAPANESE
いい天気じゃない?
BACK INTO ENGLISH
Is not it nice weather?
INTO JAPANESE
天気がいいじゃないですか。
BACK INTO ENGLISH
The weather is nice, is not it?
INTO JAPANESE
天気はいいですね。
BACK INTO ENGLISH
The weather is nice, is not it?
That didn't even make that much sense in English.