Lay summary
Emergency department (ED) crowding, with its consequent impact on patient care, policy, staff wellbeing, and financial costs, represents a societal challenge felt globally. It's frequently worsened by fluctuations in patient volumes due to weather and special events. However, the predominance of research from Western contexts leaves a gap in knowledge for unique settings like New Zealand, which faces distinct climate, geographical, rural, and equity issues, particularly for marginalised groups like Pasifika and Māori communities. Our investigation addresses this issue using a data-driven approach, creating predictive models for major New Zealand hospitals. These models allow EDs to anticipate patient volume changes, enabling effective preparation and increased operational efficiency through benefits, including optimised resource allocation, reduced treatment delays, and improved patient outcomes. Our research is crucial for advancing efficient and equitable emergency service provision and informing healthcare policies, creating profound societal impacts across New Zealand.