A Raspberry Pi climate early warning system demonstrates how low-cost environmental sensing, local logging, and edge computing can support climate resilience, disaster preparedness, and SDG 13: Climate Action. This project combines a Raspberry Pi with sensors for temperature, humidity, atmospheric pressure, rainfall, and water levels to detect emerging hazards such as floods, storms, heat stress, and compound climate risks. While the prototype is not a certified public warning network or substitute for official emergency systems, it shows how distributed monitoring can make local environmental change more visible before hazards escalate. The article connects the build to environmental monitoring systems, intelligent infrastructure, climate change as a planetary boundary, freshwater risk, planetary boundaries, and sustainable development, showing how practical data infrastructure can support earlier observation, better preparedness, and more resilient communities.