As regional climates warm in the Pacific Northwest, USA, flow minima and temperature maxima may become more synchronous in headwater streams over time. The dual stresses from lower flows and warmer temperatures will be energetically costly for cold-water species such as Coastal Cutthroat Trout and Coastal Giant Salamander. Individual fates will depend on environmental and individual characteristics, as well as the duration of exposures. In this study, I focus on stress responses and behavior of trout and salamanders as response variables to disentangle the impact of changing hydroclimate and its consequences for these sympatric stream-dwelling animals. By testing the synchrony between flow-minima and temperature maxima with mesocosms under a controlled setting, I provide insights about the short-term individual animal responses to the anticipated hydroclimate. Specifically, weight loss may not indicate long-term consequences of environmental-extreme exposure. Other metrics that relate to the animals physiological condition, such as RAMP and glucose may aid in understanding the implications of prolonged drought, but further research is necessary to establish baselines to understand this relationship. Managing for the maintenance of individual variation through population connectivity will increase the likelihood of continued persistence under anticipated drought conditions. Ultimately, investigating how individuals persist under environmental extremes in headwaters will allow better understanding of population-level responses to climate change.