Hi, Peno!
Since Nordhaven is based on RL northern slavic type places (think Sweden, Norway, Denmark, etc.), it's a good guess that even during the the warmer parts of the sim year the temps will stay cooler. I'm guessing that it will generally be between warm-freezing, depending on the time of both the day and the calendar. The devs may surprise us with a few hot days during the Summertime mid-afternoons, too; we'll see.
My understanding of Ravenwood, though, is that they didn't forget to add seasons there, rather, because that world is based around Dracula's Transylvania, they decided to keep it warm to freezing (depending on the season), with not many hot afternoons at all. (I haven't play through a full sim year there, so not positive on this yet; just going from what I recall of the discussions when it was first released.)