Since the last century, the continuous increase in human pressures such as climate change and land use have been driving biodiversity loss in freshwater ecosystems, often surpassing declines observed in other biomes. While impacts of climate warming have been well studied in some systems, the effects of extreme weather events such as heat waves and storm flows, and their potential interactions with other stressors, remain poorly documented. This study aimed to assess the combined (cumulative) effects of extreme weather events and watershed land use on stream fish communities in Quebec, Canada. Fish communities were surveyed 10 times between April and October 2024 in 12 small streams varying in watershed land use from relatively forested to highly agricultural. Our objectives were to evaluate seasonal variation in communities, determine if extreme weather events affect these communities, and assess whether extreme weather events have stronger effects in agricultural watersheds, which are already warmer and more hydrologically unstable. Our results suggest that communities are quite stable over a growing season and vary much more spatially (with land use) than temporally (depending on extreme weather), despite record heat waves and storm flows affecting Southern Quebec in 2024. Nonetheless, some longer-term seasonal trends were observed, such as shifts in body size distribution whereby the largest individuals of some species were only found during the spring. This study provides one of the few datasets in which fish community composition in small streams was monitored at regular intervals over several months to evaluate the impacts of extreme weather events on headwaters.