I do believe that splitting wood in 22º weather is easier than during sustained temperatures above 32º. It could also be that it's been below freezing for a few weeks. I can definitely say, the same rounds are splitting easier than last month when it didn't really feel like winter.
A sunny day in the 20s splitting wood is a good one for me, except if I encounter a round where the grain isn't straight.
	
		
			
		
		
	
				
			A sunny day in the 20s splitting wood is a good one for me, except if I encounter a round where the grain isn't straight.
	
	
, the better it splits when good and frozen.  Dry pine or fir, it doesn't seem to matter much, but it splits pretty easily anyway.