Space Weather is an umbrella term for phenomena observed in the near-Earth space (magnetosphere), in the Earth’s atmosphere (ionosphere and lower atmosphere), and even in the upper lithosphere related to variations in solar activity (solar flares, coronal mass ejections etc.) and the interplanetary medium. Space Weather is one of the main drivers of ionospheric disturbances which, in turn, can drastically affect the quality of the signal between a ground-based device and GNSS satellites. Two research projects are currently being carried out at IA/University of Coimbra that are aimed at studying space weather-driven variations in the ionosphere over the Portuguese territory (Continental Portugal, Azores, and Madeira) and the potential consequences for users and operators of GNSS-based services. The purpose of this workshop is the dissemination of the preliminary results of both these projects to a wide community of operators and users of GNSS-based services.