Wow, nice work Dave.  It demonstrates how the Northern hemisphere is more extreme (both hot and cold) than the southern.  I must say that that 38 degree Fort Yukon maximum really amazed me, as did the 49 degree North Dakota reading.  Interesting also that the northern hemisphere wins for extreme cold, although I guess this is because of the altitude of the Antarctic landmass, meaning that the southern hemisphere cold records are all at altitude.

By the way, I also found another Australian record which would beat the existing listed cold record for the 15-25S latitudes:  Kalpowar Forestry (Queensland, 24.69 degrees S, altitude 355m) has recorded -8.9 C.