The CYHZ METARS around the time of the crash were as follows:
While in the hold at ATURO
CYHZ 290300Z CCA 34019G25KT 1/4SM R14/P6000VM0300FT/N +SN DRSN VV003 M06/M07 A2962 RMK SN8 /S09/ SLP038
which at 1/4 SM was below minimums, hence the hold.
Then while on approach or just before leaving the hold, a nonscheduled observation was done:
CYHZ 290313Z 34020G26KT 1/2SM R14/3500V4500FT/N SN DRSN VV003 M06/M07 A2963 RMK SN8 SLP040
although vertical visibility remained at only 300 feet AGL, the visibility had increased.
However runway 05 has a LOC/DME approach (no glide slope signal) with an MDA that gets down to 277 feet over the runway, and a minimum visibility of 1 SM. So unless AC was approved for lower visibility approaches, the visibility was below minimums for 05.
The aircraft was reported to have reached the runway at approximately 0330z.
Then on the hour after the accident aviation occurrence
CYHZ 290400Z 34019G54KT 3/4SM R14/5000VP6000FT/D -SN DRSN BKN007 OVC010 M06/M07 A2964 RMK SF7SC1 SLP045
While the ceiling rose from 700 feet vertical visibility to 700 feet AGL a half hour after the event, I wonder if the gusts had already increased considerably from the 26 knots at 0313z to the 54 knots at 0400z. The abrupt abatement on short final of a strong gust which had been present while on final approach could have robbed the aircraft of lift when it was just short moments short of the threshold. At 120 knots an airbus covers 2 NM, or 12000 feet per minute, so 1100 feet is only 1/10 of that, or about 12 seconds of flight. If on glide slope they should have been 150 feet above threshold elevation at the point where they made impact with the earth, though given the gust they should have come in a bit above glide slope.
On the airport runway diagram Low Visibility Procedures (RVR less than 1200 ft to 600 ft) page it states:
Arrivals are permitted on rwy23 for approved operators down to RVR 600.
Now the RVR seems to have been well above that, so approaches could be made to other runways, given visibility met minimums.