Is "north to south" a more common set phrase than "south to north"?

Would you describe Japan as a long country "from south to north", or "from north to south"? I suspect that "from north to south" is more common, and Google ngram agrees, but is this is the case?

The "natural" order in such pairs is:
left - right
up - down
north - south
east - west
forward - backward
fore - aft
...

and not the other way.

From north to south sounds more natural to my ears. In fact, when I checked the Ngram, I was a bit surprised to find so many instances of from south to north. However, when I investigated further, I realized why: sometimes, you need to say south to north. For example, when a river flows from south to north, that's the easiest way to describe the flow of the river. Also, many of the hits were simply orienting the reader, this this one:

The main towers, from south to north, are Sister Superior, North Sister, Chimney Spire, and Baby Sister.

The same would be true when describing a south-to-north migration, or shipping route, or moutain ascent.

So, I'd guess that from north to south would be more common when you can use either one:

The nation of Chile runs from north to south.

Sometimes, however, you don't have the liberty to choose the order of the directions:

We traveled through Chile from south to north.

That might explain why the gulf in the Ngram between north and south and south and north is much wider than the gap between north to south and south to north:

What sort of evidence are you looking for?
You can collect anecdotal evidence here, or you can search a corpus.

From the British National Corpus :

North to south: 65 results.
South to north: 15 results.

So that corpus seems to agree with your intuition.