Dialogue is not just quotation. It is grimaces, pauses, adjustments of blouse buttons, doodles on a napkin, and crossings of legs
When writers are self-conscious about themselves as writers they often keep a great distance from their characters, sounding as if they were writing encyclopedia entries instead of stories. Their hesitancy about physical and psychological intimacy can be a barrier to vital fiction. Conversely, a narration that makes readers hear the characters' heavy breathing and smell their emotional anguish diminishes distance. Readers feel so close to the characters that, for those magical moments, they become those characters.
If the atmosphere is to be foreboding, you must forebode on every page. If it is to be cold, you must chill, not once or twice, but until your readers are shivering.