Ice and wintertime play an interesting role not only in Hazel’s death but in the entire book. If I remember correctly, the night that Hazel dies is a mild spring night, and the ice on the marsh would have been thawing.
One of the things that stands out about Kinbote’s recollections of Zembla is that in all the flashbacks he presents from that land, the weather is sunny and warm. Winters in Zembla would be nasty, indeed, and even summers would tend to be cool, yet Kinbote’s memories portray it as a near-tropical place in terms of weather. And he is also more sensistive to cold than we would expect of a Zemblan, as he tries to get the heater in Goldworth’s house to be more efficient. Perhaps this evidence shows little more than the fact that Kinbote is inventing Zembla during the summer time in New Wye, and the sunniness of his surroundings is intruding on his fantasy.
Another note to this issue is that the first time Kinbote sees Shade, it is on a cold, icy day, and he compares Shade to old man winter, as if Shade is the one whose natural element is the cold, instead of vice versa as we would expect of a former resident of a “northern land.”
I don’t have any real point here except that these things seem interesting, and I wonder if anyone else feels that perhaps they are connected in some way?