If we want to be absolutely pedantic, Penrith "only" managed to get to 39.9, but I'm guessing that the missing 0.1 degree wasn't exactly noticeable.
I aspire to the level of pedantry which only you can achieve :)
I'd be more disappointed if something similar happened in Adelaide tomorrow, given that another 40 would take this month to outright second on the list for most 40s in a month in Adelaide (it has already set a December record). That said, the forecast 39 looks a bit on the high side to me at this stage.
What does your crystal ball tell you about the latter part of next week, then?
(And the Sunday after New Year when the Arrows may or may not get around to unofficially running the Summit to Sea route - the trail running group version looks like it's not happening until Jan 17th.)
At this stage looking hot until New Year's Eve, cooling after that, but timing and strength of the cooling still somewhat uncertain.
May as well bring your swimsuit then. We're probably going to downgrade to a shorter run also. The royal "we" are certainly not up to running 34km!