The Rohingya refugee response in Cox's Bazaar, Bangladesh, is unique not only in terms of the rapidity and scale of the 2017 influx, but also in the extent of exposure of the refugee camps to seasonal variability, extreme weather and natural disaster risk. One of the most disaster-prone countries in the world, Bangladesh each year experiences a high degree of seasonal variety, including the southwest monsoon and two cyclone seasons. With its long coastline on the Bay of Bengal and with a landscape consisting of flat deltaic plains and sandy hills, Cox's Bazaar is highly exposed to natural hazards and extreme weather, including cyclones, torrential rain, landslides, flash floods, storm surges and extreme temperatures. Although no cyclone has made landfall on the south-eastern coast of Bangladesh since the influx of the Rohingya, 2018 saw several depressions and tropical cyclones occurring nearby in the Bay of Bengal. While the center (area of the storm with highest impact) stayed away from the coast, given the large size of these depressions and tropical cyclones, impact from strong winds and heavy rainfall extended inland. The 2018 Cyclone Preparedness Lessons Learnt Exercise aims to capture and analyse knowledge acquired by humanitarian actors during their cyclone preparedness efforts and operations in the Rohingya refugee camps during the 2018 cyclone seasons. The purpose is to provide a reference document for planning for future cyclone seasons, support evidence-based advocacy, and identify gaps in preparedness which need to be addressed in advance of the 2019 cyclone seasons. The report focuses on lessons learnt in the refugee camps, not host communities. The present report has been produced jointly by the DRR Technical Advisory Unit of United Nations Development Programme (UNDP) in Cox's Bazaar, Bangladesh Red Crescent Society (BDRCS), American Red Cross and the International Federation of the Red Cross and Red Crescent Society (IFRC). It is based on document review, participatory observation, discussions and interviews with the ISCG secretariat, sector coordinators and their teams, community members, government officials and staff from UN agencies, Red Cross and Red Crescent Societies, and NGOs. The additional inputs to the analysis and report provided by Translators without Borders, Internews, and the Columbia University International Research Institute for Climate and Society (IRI)/NASA "COMPAS" project supported by the NASA Earth Science Division Disasters Program are gratefully acknowledged. Thanks to IOM for photo-sharing.