Streamflow patterns vary by the time of year at many locations.

Monthly and yearly streamflow patterns

The U.S. Geological Survey (USGS) has been measuring streamflow at thousands of streams for over a century. When extensive records of past streamflows exist, it is possible to see a pattern of streamflow variation by month and season. Of course, every stream exhibits its own unique patterns, each stream "resides" in its own spot on the Earth's landscape, and each reacts differently to weather conditions, such as precipitation, seasonal differences, and evaporation.