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ABSTRACT Wildfires are a natural disturbance agent in the Pacific Northwest but are occurring more frequently and over larger areas in part due to climate change. Understanding environmental responses to wildfire and the interconnections between riparian and stream environments is critical for forest management. Using an extensive dataset that includes up to 10 years of prefire data, we quantified the effects of wildfire on stream temperature and shade during the first summer following the 2020 Holiday Farm Fire, which was one of the most severe fires on the westside of the Oregon Cascade Mountains in modern history. We report pre‐ and postfire maximum stream temperatures across varying burn severity for 20 long‐term monitoring sites and shade measurements for a subset of these sites. Stream temperatures increased along a gradient of low‐ to high‐burn severity. Using a linear mixed‐effects model, we estimate 2021 maximum 7‐day average maximum (7dAM) stream temperatures increased on average 0.45°C for each 10% increase in moderate/severe burn across long‐term monitoring sites. A before‐after control‐impact (BACI) analysis of maximum 7dAM showed an average increase of 3.3°C for high‐burn severity watersheds. Sites classified as high‐burn severity also showed shifts in the hourly temperature distribution and increases in temperature percentiles, with larger increases at higher percentiles. Ongoing postfire monitoring will assess potential longer term impacts of the fire on riparian shading and stream temperature and will help us to better understand the resilience of aquatic ecosystems to wildfire.