At the St.Bernard winter begins about Michaelmas, and the falling of snow in September; when the Englishmen already mentioned crossed the mountain at the end of August, they found almost no snow on their road, but the slopes on both sides were covered with it.
Hannibal thus appears to have arrived at the pass in the beginning of September; which is quite compatible with the statement that he arrived there "when the winter was already approaching" -- for -- sunaptein ten tes pleiados dusin-- (Pol.iii.

54) does not mean anything more than this, least of all, the day of the heliacal setting of the Pleiades (about 26th October); comp.
Ideler, Chronol.i.

241.
If Hannibal reached Italy nine days later, and therefore about the middle of September, there is room for the events that occurred from that time up to the battle of the Trebia towards the end of December (-- peri cheimerinas tropas--, Pol.iii.

72), and in particular for the transporting of the army destined for Africa from Lilybaeum to Placentia.

This hypothesis further suits the statement that the day of departure was announced at an assembly of the army -- upo ten earinen oran-- (Pol.iii.