The most recent of the year I have ever sown carrots was when I once stumbled upon a carrot variety that should be able to be sown in August, germinate during the fall and give fresh crunchy roots the following spring. I therefore immediately pulled in a manure bench and sowed in August, they sprouted during the fall - and died of frost in February. Only a single measly little mess survived that winter, after which I dropped its kind of experiments and went over to early spring sowing in manure bench instead.
On the other hand, it can also get a little boring just to stay safe. When I got some new bags of early carrot seeds home a few months ago, I suddenly discovered that on the back it said that you could also sow in October-November for an early spring harvest. And it was not seeds from an English company with their warmer climate, but rather from Swedish Impecta. I have since googled and googled and have not been able to find anything about sowing carrots as late in a climate as ours - but Impecta probably does not write like that just to make fun of us :-) So it must be tried - especially since the manure bench as carrots still have to be sown in until the spring has just been cleared of the basil. If the experiment fails completely, it can just be re-seeded until March.