Hmmm.... no one responding? :?
By "hudan," do you mean 普段(ふだん)? I don't know whether it is correct or not, but I usually spell that "fudan" in romaji. Anyway, here goes:
普段、(一年の内)この時期は暖かいです。
Fudan, (ichinen no uchi) kono jiki wa atatakai desu.
The part in parentheses is not really necessary.
Or:
この時期は、普段暖かいです。
Kono jiki wa, fudan atatakai desu.
HTH!!