Unravelling how a multiplicity of global change factors might influence the expansion of alien plants is a major goal of invasion biology. In this article, the association of climatic conditions and water quality, with blooms of the invasive fern Azolla filiculoides in the Doñana marshland, one of the most extensive wetlands in Europe, are explored. Azolla annual cover has been quantified through remote sensing since its first detection in 2001. In the last decade there has been a considerable increase of orthophosphate and yearly fluctuations of nitrate. The first orthophosphate increase coincided with the presence of Azolla in Doñana. Since then, there has been a positive relationship between inter-annual variation in Azolla cover and minimum temperature during the coldest months. This study shows that the Doñana marshland is facing rapid eutrophication and invasion by Azolla, most notably in years with high temperatures during the winter. informacion[at]ebd.csic.es: Espinar et al (2015) Linking Azolla filiculoides invasion to increased winter temperatures in the Doñana marshland (SW Spain). Aquatic Invasions (2015) Vol 10, 1: 17–24 http://dx.doi.org/10.3391/ai.2015.10.1.02