On 14 July 1915, "Endurance" was swept by a southwest gale, with wind speeds of , a barometer reading of and temperatures falling to . The blizzard continued until 16 July. This broke up the pack ice into smaller, individual floes, each of which began to move semi-independently under the force of the weather, while also clearing water in the north of the Weddell Sea. This provided a long fetch for the south-setting wind to blow over and then for the broken ice to pile up against itself while individual parts moved in different directions. This caused regions of intense localised pressure in the ice field. The ice began "working", with sounds of breaking and colliding ice audible to those on the ship through the next day. Breaks in the ice were spotted but none approached the ice holding the "Endurance".