Though cumulative emotional and physical effects of disasters may diminish evacuees' short and long-term mental and physical health, social factors may buffer such consequences. We approached survivors of the October 2007 San Diego, California firestorms. We gathered data during the evacuation and 3 months afterward. Questionnaires measured social support as well as PTSD, depression, and anxiety symptoms. Saliva samples were used to assess the stress hormone, cortisol. Analyses, adjusting for age, gender, and socioeconomic status, showed PTSD symptoms were associated with flattening of the diurnal cortisol rhythm during evacuation. Secondary analyses showed those reporting a family emphasis on moral and religious values had lower psychological distress. Though anxiety symptoms had significantly decreased in the overall sample at follow-up, blunted cortisol rhythms persisted among those individuals with continued high anxiety. Results highlight a possible psychological, and perhaps a physiological, benefit of social and existential factors in disaster situations. Future work should explore the role of psychosocial factors and stress physiology in the development of long-term health concerns among individuals exposed to disaster.