FireLog: An open-source, low-cost system for temperature logging during wildland fires with high spatial and temporal resolution.

Measuring flame, air, and soil temperatures during wildland fires, including wildfires and controlled burns in land management contexts, is crucial for research and applications in fire ecology, safety, and management in a wide array of ecosystems, from grasslands to forests. However, open-source and commercial systems are needed for measuring and logging flame and air temperatures that are user-friendly, economical, modular, and customizable. This paper details the design, development, and validation of the FireLog system. Laboratory validation experiments demonstrated high measurement accuracy, with a minimum coefficient of determination (R2) of 0.98 and the highest observed root mean square error (RMSE) of 29.5 °C when compared with a Campbell Scientific data logger in furnace tests spanning 20-1000 °C. These results confirm the FireLog system's precision, repeatability, and robustness under controlled conditions. Field deployment during prescribed burns further validated its operational performance, confirming its ability to record temperature dynamics reliably in active fire environments. FireLog represents a practical and scalable tool for researchers and practitioners in fire science and land management.