File:Freeze-up on James Bay (MODIS 2023-12-27).jpg

English: The annual winter freeze-up of James Bay was well underway on December 25, 2023, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired a true-color image of the icy scene.

James Bay is the shallow southern-most extension of Hudson Bay, which is an inland extension sea of the Arctic Ocean. Located in Canada, the Bay sits between the provinces of Ontario (west) and Quebec (east) but is politically part of Nunavut. Stretching 275 miles (443 km) in length and 135 miles (217 km) wide, most of James Bay is less than 200 feet (60 meters) deep. The Bay receives freshwater from many major rivers, especially near Akimiski Island, the largest island in James Bay, where mudflats and freshwater inflow tint the waters with typical tan and green tones of sediment. The swirling sediment is visible even under the forming ice.

Freeze-up in James Bay typically begins in late November or early December and lasts about 50 days. By early January, the freeze-up is complete. Ice first begins to form on the water between Akimiski Island and the western coastline, followed by the formation of landfast ice around Akimiski Island, especially in the west, and along the western and southern coastlines. Ice then begins to cover the coves along the eastern coast while free-floating sea ice may form in open water. Eventually the entire Bay becomes covered with a sheet of ice thick enough to be used as a wintertime roadway for travelers from one coast to the other. Freeze-up may begin slowly, but tends to accelerate near the winter solstice, when daylight is the shortest.