What are some reasons for a LARGE temperature difference between the high and the low?

Question

ook...why does that affect it?

Answer 1

Pressure and temperature are related, so when you have an airmass with a lower pressure it will also possess a different temperature.  

So, when you have very pronounced upper level ridging or troughing, you also have a more pronounced changed in pressure and temperature.  If you ever look at a weather map of jet streams or a 500mb map and you notice it is very wavy, up and down, up and down, then you can expect one region to be very hot and dry and another region to be experience some sort of precipitation and below normal temperatures.

Answer 2

Dry air, dry soil surface, light winds, high pressure systems, clear skies.