Hudson Bay sea ice coverage is only slightly below average for this time of year (week of 14 May, below) but well above levels for 2006, when Western Hudson Bay breakup was relatively early).
Even at its highest extent in April, Hudson Bay is only 97-98% ice covered (due to persistent shoreleads and polynyas), which means ice levels are currently only 10% or so below maximum. In other words, there is still lots of polar bear hunting habitat over the bay.
That’s a bit lower than ice coverage was for the last two years at this date (2013-2014), which had average or above average ice cover. However, there is currently a bit more ice on Hudson Bay than there was in 2011 and 2012 – and much more than there was in 2010 and 2006.
Note that in mid-late May 2013 (Fig. 2), sea ice was breaking up in southwest Hudson Bay, around Churchill, as well as along the east coast.
The difference from 2015 is almost certainly due to currents and prevailing winds (known to drive the formation of spring polynyas, as discussed in my last post regarding open water in the Beaufort Sea), not temperature (Danielson 1990).
Breakup of sea ice over Hudson Bay usually proceeds from the east and north, with the last remaining ice converging on the southwest shore (Fig. 3, discussed previously here). The pattern and ultimate date of breakup is highly variable year to year (Fig. 5).
Danielson Jr., E.W. 1990. Hudson Bay ice conditions. Arctic 24(2):90-107. pdf here.
Stirling, I., Lunn, N.J., Iacozza, J., Elliott, C., and Obbard, M. 2004. Polar bear distribution and abundance on the southwestern Hudson Bay coast during open water season, in relation to population trends and annual ice patterns. Arctic 57:15-26. http://arctic.synergiesprairies.ca/arctic/index.php/arctic/article/view/479/509