Despite decades of climate change research, we still lack an understanding of how temperature changes will alter metacommunity dynamics. One challenge is that changing temperatures can influence metacommunity dynamics through multiple pathways. Metabolic changes at the level of individuals can scale to alter population dynamic rates and community interactions. This can lead to deterministic changes, but also stochastic ones, as relative abundances in small populations tend to exhibit greater ecological drift that generates spatial and temporal variation independent of environmental heterogeneity. Finally, these effects can all be modulated by dispersal. Here, we present hypotheses for metacommunity dynamics across temperatures and assess them using a temperature-dependent, stochastic community model. Each simulated species is assigned a “body size” that determines how temperature sets key demographic processes such as survival and density-dependence. The model is parameterized with data from year-long spatial surveys of tropical and temperate stream macroinvertebrates, allowing us to explore how metacommunities might respond to simultaneous changes in thermal regimes and spatial connectivity. Our analyses focus on temporal β-diversity to quantify compositional changes through time - a key indicator of community assembly processes in metacommunities. Simulated warmer communities tend to have smaller sizes compared to colder ones because warmer temperatures and accelerated metabolic rates lead to lower survival and carrying capacities. Smaller communities show greater compositional variability, reflected in higher temporal β-diversity. Increasing the probability of dispersal recruitment leads to larger community sizes and reduces the range of community sizes exhibited. Dispersal increases community sizes in our model, reducing community variability and temporal β-diversity. This effect is seen in both warmer and colder parameterizations. Thus, communities that show predictable local recruitment, are well-connected to other sites via dispersal, and/or are composed of organisms with high overall dispersal rates, will show lower ecological drift and temporal β-diversity as temperatures increase.