Understanding temporal variation of host–pathogen dynamics can be important for predicting disease risks and anticipating how disease systems may change in response to natural or human disturbances. Seasonal changes in weather, especially those associated with changes in temperature or precipitation, are often a key component of temporal changes in infection risk and can have important impacts on disease systems. However, these patterns can be difficult to track due to interannual variation and the need for longer term, multi-year surveillance efforts. We assessed seasonal and annual changes in the trematode component community of first-intermediate host stream snail Elimia (= Oxytrema = Goniobasis) proxima across 5 streams in the southern Appalachian Mountains. Over 3 yr, we found no evidence of consistent seasonal peaks of trematode infection in E. proxima. There was some across-site consistency in infection prevalence over 4 yr, because high prevalence sites tended to maintain higher prevalence from year to year, relative to lower prevalence sites. In addition, we examined the relationship between prevalence of first-intermediate host infection, weather variables, and site-level factors, including snail density and water quality metrics. Trematode prevalence was negatively related to total precipitation, which may have been due to the movement of infectious parasite stages and hosts downstream during high flows. We found no strong relationships between trematode prevalence and snail density or any of the water quality metrics examined in this study, indicating that snail infection may be driven primarily by definitive host activity.