This short paper explores the design of context-aware urban citizen science systems to address the challenge of sustained participant engagement. Building on a pilot study conducted in Zurich involving citizens in urban heat island detection, we investigate engagement barriers and patterns. Grounded in Information Systems (IS) Continuance Theory and leveraging Just-In-Time Adaptive Interventions (JITAIs), we follow a design science research approach and propose initial design requirements and principles for enhancing citizen science systems. These principles include context-aware participation timing, real-time feedback, and adaptive task complexity, aimed at fostering satisfaction, perceived usefulness, and expectation confirmation. Our initial pilot study insights and theoretical analysis indicate that contextual factors may play an important role in moderating user engagement and system interactions. We conclude with insights on system design that align with theoretical models of IS continuance, offering guidance for practical applications and future research in developing context-aware citizen science platforms.