Windy day

It's really windy today . >Perfect
I feel scared on a windy days like today. > You aren't scared on just one day that is like today, so you need to make "day" plural.
But on the other hand , I feel a little bit excited a little bit. >There should not be a space between the word "hand" and the comma. Also, we put "a little bit" before the word it modifies, in this case "excited."
I am going to stay at home today , >You need a period, and it needs to be right after "today."
I hope people in Kumamoto can sleep well tonight. >If this is a general wish, you don't need the "can." If your wish is because the wind might interrupt their sleep, this is perfect.