Below are the synoptic weather maps for Australia for 11 August 2015 and 12 August 2015. There are no weather fronts, or adverse weather in the western two-thirds of the continent.

Alice Springs (lat:-23.8, long: 133.89) is in the centre of the continent. It's weather observations for 11 August 2015 reveal the temperature ranged between $5.8$ $^oC$ and $26.0$ $^oC$ and the dew point range was between $-18.8$ $^oC$ and $-2.5$ $^oC$.

Similarly for Darwin (lat: -12.42, long: 130.89), which is located on the coast in the sub tropics, in the central north of the country, the temperature range for 11 August 2015 was $19.7$ $^oC$ to $30.1$ $^oC$, while the dew point range was $15.4$ $^oC$ to $19.8$ $^oC$.

Perth (lat: -31.93, long: 115.98), on the southern western coast has a temperate Mediterranean climate. It's temperature range was $10.2$ $^oC$ to $17.6$ $^oC$ and the dew point range was $5.7$ $^oC$ to $11.7$ $^oC$.

Adelaide (lat: -34.95, long: 138.52), on the southern coast, in the centre region , also has a temperate climate and its temperature ranged from $7.6$ $^oC$ to $15.4$ $^oC$ and the dew point range was $-0.3$ $^oC$ to $8.5$ $^oC$.

Lastly, Brisbane (lat: -27.39, long: 153.13) which is on the east coast had temperatures between $8.2$ $^oC$ and $21.9$ $^oC$ and the dew point varied between $6.9$ $^oC$ and $15.8$ $^oC$.

All these weather observations show significant variance in the dew point for these locations given the respective temperature ranges and the lack of weather fronts and adverse weather systems.