Introduction: Tobacco smoking is a pressing US public health concern, necessitating effective cessation strategies. The rise of electronic cigarettes has spurred increased dual use of cigarettes and e-cigarettes, prompting inquiry into its potential for shifting smokers to e-cigarettes. This novel study examines the role of affect and affect dysregulation in influencing longitudinal smoking patterns among early-stage US adult dual users. Methods: We analyze data from an ecological momentary assessment (EMA) study of dual users, wherein real-time mood assessments of ‘urge’ (Urge), ‘positive affect change’ (PAC), and ‘negative affect change’ (NAC) were collected alongside smoking behaviors for a week. A two-stage mixed-effects location scale model is utilized to assess mean and intra-individual variability in EMA mood assessments as predictors of trends in cigarette and e-cigarette usage subsequently tracked using biweekly surveys for up to a year. Results: Results indicate that dual users who experience higher mean levels of Urge and PAC with respect to cigarette events, as well as greater intra-individual mood variability in Urge and PAC during the EMA week, are at a higher risk of experiencing subsequently lower e-cigarette adoption. Surprisingly, dual users with higher mean levels of NAC during EMA cigarette events and greater intra-individual variability in NAC during EMA week exhibit higher future e-cigarette adoption and cigarette use reduction respectively. Conclusion: This study yields insights into mood dynamics during early e-cigarette adoption among dual users. Identification of specific EMA mood assessments predictive of future trends in cigarette and e-cigarette use aids early-stage targeted intervention strategies for smoking cessation. Nuanced understandings of longitudinal smoking patterns among dual users also enhance the ongoing debate about e-cigarettes’ cessation efficacy.