The central concept of Koth is that of an enormous sphere surrounding two polar celestial bodies – one light ‘sun’ and one dark ‘sun’, with a smaller ‘twilight star’ between. The actual radius of this sphere is much more than an AU – though the ‘light sun’ (commonly referred to as Suyis) is far larger and hotter than Sol, the ‘dark sun’ (Nothis) absorbs enough energy to keep the wide belt between Suyis and Nothis habitable. Since the inner surface of Koth does not rotate, Day and Night are not times of day but rather locations. As such, time in Koth is rather fluid on a daily basis – however, Koth does have seasons.
The ‘Twilight Star’ (Golus) has a number of satellite moons which orbit perpendicular to the line between Suyis and Nothis. Two of these, Yeltis and Guevis, are exactly opposed in position, with Golus always immediately between, and each reflects the light of a given solar body differently. When Yeltis is in a position to reflect the light of Nothis upon a given part of Koth, the weather is cooler – conversely, when Guevis reflects Suyis, the weather warms.
The average local climate of any given area is ordinarily governed by two factors – the area’s proximity to Suyis, and the area’s proximity to Nothis. Thus, the area closest to Nothis, or the “North”, is frigid and cold, whereas Suyis’ “South” is hot. While this is largely true, exceptions abound. First are the areas near “moons”, large statites (like satellites, only stationary) that hang motionless above the surface of Koth. These moons block the light of Suyis and Nothis in certain areas, and thus create light and dark zones to their North and South. To a lesser extent, this effect also appears near mountains on the surface of Koth. Areas where Suyis is blocked are called “shadows”, whereas areas where Nothis is blocked are called “antumbras”.
Another exception to the generalities of climate is the areas created by trods. The dimensional space near Koth is exceptionally porous, such that holes between planes are frequent, as are areas of overlap. Even in the North, there are areas near the plane of Fire which are far warmer than average, as an example. The planes are often thought to be related to the satellites of Golus, as listed here: