The constellation Cepheus is visible in the Northern Hemisphere throughout the year. However, it's best viewed in the autumn (September-November), when it's highest in the sky.

Here's why:

* Circumpolar Constellation: Cepheus is a circumpolar constellation, meaning it never sets below the horizon for observers in the Northern Hemisphere. This allows you to see it year-round, but its visibility varies.

* Autumn Peak: While visible throughout the year, Cepheus reaches its highest point in the sky during autumn evenings. This makes it easier to spot and observe, as it's less affected by the twilight and is higher above the horizon.

So, while you can technically see Cepheus any time of year in the Northern Hemisphere, the best time to catch a good view is during autumn.