It feels like it's cold enough to put the heat on first thing in the morning, but then I feel like I need the AC during the day because it's that hot.
この場合、次のような言い方ができますよ。
ーIt feels like it's cold enough to put the heat on first thing in the morning, but then I feel like I need the AC during the day because it's that hot.
「朝方は暖房を入れるくらい寒いが、日中は冷房が必要なくらい暑い」
first thing in the morning「朝一番・起きがけ」
during the day「日中」
ご参考まで!