"For the better"

I had this argument thingy with my English teacher, because I used "For the better" in a sentence. ("Even though the weather is nice, it is for the better not to forget your umbrella".) Now, I know it was most likely better to write "Even though the weather is nice, it's better not to forget your umbrella." but, alas, I kind of forgot about that.

So, my question is, was the first sentence correct english or not ? ^^

[Tdol]

I'm not sure if I could say it is incorrect, but it is very strained. I'd say it's just about possible as a sentence. However, it does strike me as a form that might exist in a dialect of English, but I can't say I am aware of it.