In springtime, fisherman are concerned about water temperature in the Hudson River. When the the water temperature in the Tappan Zee reaches 50 degrees, migrating striped bass transition from brackish to freshwater and continue their journey upriver where eager fisherman await them with bait and lures. An easy way to learn about water temperature is by checking the network of river gauges along the Hudson, which collect data on salinity, acidity, turbidity, water level as well as temperature. Current conditions are shown on the Stevens Institute website: For the past few days, water temperature at Piermont Pier has been fluctuating between 48 and 55 degrees. Upriver at Norrie Point, water temperature is a couple of degrees cooler, between 45 and 52 degrees.