In reply to George1924:
On average, if using skis then April into May. If not, mid/late May into June. Possible some years into early July but will need a much earlier start.
However, each year is a bit different - 2022 had warm temperatures a lot earlier (bringing season forward), 2023 had a lot of late season (April/May) snow.
Main requirements are neve on the face (so not black ice) and decent overnight freeze. It is prone to rockfall when warm.
Hope this helps.