This talk was given at the 25th International SST Users’ Symposium and GHRSST Science Team Meeting (GHRSST25) held in Montreal, Canada/Online from 10 – 14 June 2024. Explore the full program at GHRSST25 on the GHRSST Website here. Abstract Fiducial Reference Measurements (FRM) are high-quality, calibrated and SI-traceable reference in situ measurements needed for the validation of climate-quality or reference satellite Sea and sea-Ice Surface Temperatures (SST/IST), such as from Copernicus Sentinel-3 Sea and Land Surface Temperature Radiometers (SLSTR). Since 2018, within the frame of the Copernicus TRUSTED (www.eumetsat.int/TRUSTED) project, over 177 drifting buoys have been deployed worldwide, providing high quality in situ SST measurements towards FRM quality. Recent achievements have been the definition of an uncertainty diagram for the buoy SST measurements providing traceability to SI and updates of the platform and measurement metadata and quality control processes. Since 2022, activities have begun towards developing high quality sea-ice measurements from drifters with a newly developed prototype probe by NKE, with 16 equally spaced thermistors, now completed and under calibration and testing by the SHOM and DMI. This year sees the development of the IST drifting buoy platform which is planned to be further calibrated and tested in Qaanaaq, Greenland in winter 2024/2025. An operational service of IST measurements is expected to follow in 2026 / 2027 to support the upcoming availability of operational Day-1 IST products from SLSTR. The presentation will give an overview of the status and details of TRUSTED FRM drifting buoys for SST and IST at high-latitudes and over sea-ice, including the status of the availability of current measurements and definitions, development of new platforms / sensors, progress with uncertainty diagrams and metadata / quality control and future steps and recommendations.