Dimensional models of early life adversity highlight the distinct roles of deprivation and threat in shaping neurocognitive development and mental health. However, relatively little is known about the role of unpredictability within each dimension. We estimated both the average levels of, and the temporal unpredictability of deprivation and threat exposure during adolescence in a high-risk, longitudinal sample of 1354 youth (Pathways to Desistance study). We then related these estimates to later life psychological distress, and Antisocial and Borderline personality traits, and tested whether any effects are mediated by future orientation. High average levels of both deprivation and threat exposure were found to be associated with worse mental health on all three outcomes, but only the effects on Antisocial and Borderline personality traits were mediated by decreased future orientation, a pattern consistent with evolutionary models of psychopathology. Unpredictability in deprivation exposure proved to be associated with increased psychological distress and a higher number of Borderline traits, but with increased future orientation. There was some evidence of unpredictability in threat exposure buffering against the detrimental developmental effects of average threat levels. Our results suggest that the effects of unpredictability are distinct within different dimensions of early life adversity.