When you cast this spell, a sturdy trapdoor appears at the intended location, opening into an extradimensional space beneath the ground. A ladder descends 15 feet into a small chamber capable of sheltering the caster and up to seven other creatures. The shelter exists outside of normal space, therefore spells and effects emanating or affecting one side of the door exert no influence on the other side of the door. Storm cellar provides protection from natural hazards, such as forest fires, tornadoes, hurricanes, falling trees, thunderstorms, and blizzards. Of course, if a tree falls on top of the door, the room's occupants must contend with it when they leave the cellar. Creatures within the extradimensional space can see through the door, although creatures on the other side of the door cannot look into the room. However, creatures on the outside can force open the door with a Strength check (DC 23) or break it (hardness of 5; 20 hp). Casting other spells that create extradimensional spaces or using extradimensional items, such as a bag of holding, while within the cellar is extremely dangerous.