Water temperature is the ‘master’ river habitat variable, controlling physico-chemical and biological processes within river systems. River temperature is a key determinant of both water quality and ecosystem dynamics; it is therefore highly important to freshwater species, many of which are intolerant of high temperature extremes. Recent projections indicate that river temperatures across the globe will warm substantially under future climate change, and there are concerns that such temperature increases could have severe consequences for river ecosystems. In this context there is an urgent need to better understand space-time patterns of water temperature variability (across river ‘thermalscapes’), processes controlling river temperature dynamics, and ecological response under climate (and other drivers of) change. Previous research into river temperature patterns has focused on either the spatial or temporal dimensions because of the difficulty in observing both domains simultaneously. This means that much of our current understanding of river temperature is based on spatial or temporal ‘snapshots’. There is consequently a lack of knowledge concerning how river temperatures change and evolve simultaneously across both time and space. Often, even when simultaneous spatio-temporal temperature data does exist it is generally of coarse resolution and unsuited to understanding fine-scale influences that create patchy habitats of importance for river ecology (e.g. cold water refugia). To address these knowledge gaps, this project aims to shed new light on river temperature patterns across time and space. It will generate new understanding of the hydrological, geomorphological and geological drivers of river thermalscapes. These data will feed into the development of models and adaptation strategies for river ecosystems under climate and other drivers of change.