Increasing winter climate variability in cold regions leads to highly contrasted snowpack stratigraphy, including the frequent formation of ice layers that transiently alter meltwater infiltration and runoff generation. These features play a key role in flood risk and water resource dynamics but remain difficult to monitor at relevant temporal scales. This study investigates the hydrological behavior of an ice-layered snowpack subjected to highly variable winter conditions at the Sainte-Marthe Experimental Watershed (Québec, Canada). Between 8 February and 3 April 2023, more than 50 freeze–thaw cycles were recorded. An innovative, high-frequency monitoring system was deployed to capture both internal snowpack dynamics and boundary fluxes. The setup included a downward-looking 1.5 GHz ground-penetrating radar (GPR) operating at 2.5-minute intervals, ultrasonic snow-depth sensors, time-domain reflectometry probes at the snow–ground interface, shallow piezometers, a snow lysimeter, and soil-moisture sensors. Energy-balance variables and a disdrometer were also measured, and weekly snow-pit observations were used for validation. Two-way travel times and signal amplitudes extracted from GPR radargrams enabled detection of ice-layer formation and decay, as well as temporal changes in permeability within the snowpack. Results highlight the hydrological control exerted by ice lenses, notably during a major rain-on-snow event on 17 March, when water temporarily ponded above an impermeable layer before a progressive permeability transition allowed percolation. This study demonstrates how downward-looking GPR complements conventional snow and hydrological measurements by providing non-invasive, two-dimensional proxies of liquid-water dynamics at unprecedented temporal resolution.