Italian school buildings are characterised by ageing envelopes, high classroom occupancy, and limited availability of cooling systems, leading to increasing overheating risks during the intermediate and summer seasons, driven by climate change and more frequent heatwaves. While dynamic building simulation can support overheating assessment, its use remains limited among school owners, public administrations and non-technical stakeholders due to software complexity, modelling requirements, and computational effort.,To bridge this gap, this paper presents the School Overheating Screening (SOS), an open-source tool for public administrations and school managers to evaluate overheating risks and benchmark school climate resilience. SOS draws database of 24,960 pre-computed dynamic simulations encompassing various envelope configurations, future weather scenarios, and urban heat island effects across all Italian climate zones.,Using basic building inputs on classroom typologies, stakeholders can rapidly assess occupant thermal stress through complementary human-centric indicators, including EN 16798-2 adaptive comfort, CIBSE TM52 criteria, and heat stress day sequences. Operating at both classroom and whole-building levels, SOS allows decision-makers to identify vulnerabilities and compare the effectiveness of low-cost passive mitigation strategies. Applied to large school portfolios, SOS helps municipalities decide where retrofit budgets should go first to protect students’ health, well-being, and learning capabilities.