Coldwater refugia-- networks of coldwater patches that are expected to persist despite changing climates-- provide thermal shelter for coldwater fishes and other organisms from warming stream temperatures. Coldwater patches may originate from sources such as groundwater seeps, pools, and tributaries; however, it is difficult to predict locations of coldwater patches from coarse geographic or geologic data layers. Additionally, it is unknown how coldwater patches change in quantity and quality (e.g. size) spatially and temporally. Our objectives were to 1) quantify the heterogeneity of coldwater patch quantity and quality, and 2) determine how coldwater habitat quantity and quality change throughout the summer (June to August) with changing temperature and discharge. We identified coldwater patches using thermal infrared cameras in four small streams in western Massachusetts, USA. We conducted detailed habitat surveys within the coldwater patches and longitudinal temperature surveys through the ~1 km stream reach. Results show variability between streams across quantity and quality of coldwater patches with warmer streams having fewer coldwater patches. Coldwater tributaries created larger and more consistent coldwater patches than seeps and pools. Additionally, discharge greatly impacted coldwater patches with high flows eliminating coldwater patches and making the stream thermal profile relatively homogenous. Information about thermal habitat heterogeneity can be used to guide mapping of coldwater refugia and, when combined with fish movement data, to better understand fish use of coldwater patches. These results suggest a new approach that could develop a tool for guiding freshwater conservation decisions with changing climates.