Was looking at some of the forecast temps on the NSW coast for Monday 10th getting up to 36C. Looks to be short lived with a southerly coming through. By way of contrast, Sydney is forecast for 34C and Melboune 16C.
Frontal feature to hit Melbourne on Monday before it has any chance of diurnal heating. So timing of the front on Monday AM lends itself to such big variance IMO. It'll be warm in Sydney but I think it's open to a little downgrade later in the week. BOM really just basing that on the positioning of the High (NW winds).
How about BOM predicting Bulahdelah going for 40C on Monday. Can't see that happening. http://www.bom.gov.au/nsw/forecasts/bulahdelah.shtml
There is some bug in the BOMs MetEye. It routinely has stupid temps for Buladelah. I noticed this last summer when a few 45s were forecast. You can see on the MetEye map that it's an anomalous spec