Background <p>Seasonal and climatic variations are known to influence patterns of mental illness presenting to emergency departments; however, few studies—particularly in Saudi Arabia and the Eastern Mediterranean region —have examined these effects. This study investigates whether seasonality and gender differences are associated with variations in the number of emergency department visits for mental health disorders at Eradah Complex for Mental Health in Dammam, Saudi Arabia.</p> Methods <p>We analyzed data from patients presenting to the emergency room (ER) between January 2024 and December 2024 with mental health diagnoses according to ICD-10 criteria. Data were categorized into four consecutive quarters (Q1 = January–March; Q2 = April–June; Q3 = July–September; Q4 = October–December) and analyzed by sex. Chi-square analysis was used to assess seasonal variation.</p> Results <p>Seasonal time-series assessment demonstrated significant variation across all disorders studied, including personality disorders, mixed anxiety–depressive disorder, obsessive–compulsive disorder (OCD), and psychotic disorders. Most patients with psychotic disorders were male, whereas most patients with the other diagnoses were female. There was a significant seasonal variation (<i>P</i> ≤ 0.01) in emergency department visits for psychotic disorders and mixed anxiety–depressive disorder in both males and females.</p> Conclusion <p><b>S</b>ignificant seasonal variation exists in ED visits for psychotic disorders, mixed anxiety–depression, OCD, and personality disorders, with the highest volume occurring in Q4 (October–December). Females accounted for most non-psychotic disorders. Therefore, emergency and outpatient psychiatric services should enhance winter/autumn preparedness, and further research should examine underlying climatic drivers.</p>