YOU SAID:

I think that the weather won't change today, it will stay rainy and boring

INTO JAPANESE

今日は天気が変わらないと思いますが、雨が降って退屈しまいます

BACK INTO ENGLISH

I don't think the weather will change today, but it will rain and get boring

INTO JAPANESE

今日は天気が変わらないと思うが、雨が降って退屈になる

BACK INTO ENGLISH

I don't think the weather will change today, but it will rain and get boring