WCRP is proud of our leaders pursuing Grand Science Challenges across the range of research sectors. A session at the 2017 Joint IAPSO-IAMAS-IAGA Assembly (27 August to 1 September 2017, in Cape Town) will bring together the WCRP Grand Challenge on Understanding and Predicting Weather and Climate Extremes, the HiWeather Project of the WMO World Weather Research Programme (WWRP) and others interested in understanding and predicting weather and climate extremes. The International Association of Meteorology and Atmospheric Sciences (IAMAS) is hosting this exciting session. See the call for abstracts. The deadline for submitting an abstract is March 12, 2017.