Picture posting is enabled for all :)
Tricky one! My guesses would be (for here in the South):I think it's more a case of temperatures and what's happening in Nature around you than fixed dates (e.g. buds flowering, shoots coming up, leaves beginning to turn brown), although some crops you just have to get on with, irrespective of conditions, to give them enough time to reach maturity - but I suppose those tend to be given specific planting/sowing dates.
According to my calendar this year winter begins on 21 December - how accurate that will be in terms of actual weather I have no idea! lol ;D