The expected weather pattern across southern Australia hasn't changed significantly, with a large high pressure area off the southern coast expected to drift eastward through the weekend. This high brings cooler and drier air to New South Wales on Friday. I did raise temperatures a couple degrees for Friday and Saturday from my initial forecast.
The main change with the update was to add a mention of a possible afternoon shower on Saturday, as it appears that there will be just enough instability to allow for some showers to pop up. The best chance of showers will be over the higher terrain of the Blue Mountains, east of Bathurst. With the prevailing wind flow coming from the east, some of these showers that develop over the mountains could push west toward Bathurst late in the day. As you can see in the forecast, the chance of a shower happening at the track is low, only 20%.
The weather for the race looks great, with comfortable temperatures at the start in the upper teens C or lower 60s F. High temperatures during the race will rise into the lower 30s C or upper 80s F. There will be some cloud cover developing in the afternoon hours, but no rain is expected.