Winter stream temperatures, though infrequently studied, exert important influences on aquatic communities. To quantify effects of watershed physical characteristics on stream winter thermal regime, 54 streams (watershed area = 0.2–7.9 km²; altitude < 1300 m) on the Olympic Peninsula, Washington, USA were monitored hourly for 4 years. During the study, an exceptionally warm winter (2015) was used to evaluate influences of watershed characteristics under climatic conditions similar to those projected for mid-twenty-first century. Four watershed characteristics were hypothesized to influence winter stream temperature: stream size, elevation, solar exposure, and presence of glacial materials overlying bedrock. Larger streams were associated with colder winter water temperatures and higher thermal sensitivity to atmospheric conditions. Elevation—the strongest driver of winter stream temperatures—was negatively correlated to stream temperature, except on the coldest 15 days of winter when it had no influence. Watershed solar exposure had only a marginal influence on how cold streams were in winter but was positively correlated to diel stream temperature variation and thermal sensitivity. Streams in watersheds with glacial material overlying the sedimentary bedrock were colder and had less diel variation and lower thermal sensitivity than streams in watersheds where glacial material was not present. During the warm 2015 winter, the influences of watershed characteristics on temperature tended to be weaker compared with the other years. These insights improve our understanding of how watershed physical characteristics influence stream winter thermal regimes and how these winter thermal regimes vary across landscapes, facilitating development of predictive models, a first step in designing management plans that account for winter thermal habitat needs.

冬季溪流温度虽然很少研究，但对水生生物群落产生重要影响。为了量化流域物理特征对溪流冬季热状况的影响，共有54条溪流（流域面积= 0.2–7.9 km ²; 每小时对美国华盛顿奥林匹克半岛的海拔高度<1300 m）进行监测，为期4年。在研究过程中，使用了一个非常温暖的冬天（2015年）来评估在类似于二十一世纪中叶的气候条件下，分水岭特征的影响。假设有四个分水岭特征会影响冬季溪流的温度：溪流的大小，高度，日光照射以及基岩上覆的冰川物质的存在。较大的溪流与较冷的冬季水温和对大气条件的较高的热敏感性有关。海拔高度是冬季溪流温度的最强驱动力，与溪流温度呈负相关，除非在冬季最冷的15天没有影响。流域日光照射对冬天的冷溪流影响仅微不足道，但与di流温度变化和热敏感性呈正相关。与不存在冰川物质的流域相比，在冰川流域覆盖沉积岩层的流域中的河流较冷，且迪尔变化较小，对热的敏感性较低。与其他年份相比，在2015年温暖的冬季，分水岭特征对温度的影响趋于减弱。这些见解使我们对分水岭的物理特征如何影响河流冬季热状况以及这些冬季热状况如何在不同景观中变化产生了更好的了解，从而促进了预测模型的开发，这是设计解决冬季热栖息地需求的管理计划的第一步。