As it is something close to a matter of holy writ that rain must fall on any Scottish parade, let's get the shower over with quickly.

For although Scotland ended their autumn series on a satisfying high note, with a second win in three games and with the side firing nicely, a couple of points must be made.

The first is that they were helped along the way by the limitations of their opponents. In their different ways, Argentina, New Zealand and Tonga collaborated in Scotland's rehabilitation programme. The Pumas were far below their best, the All Blacks sent out a largely second-string side and Tonga's lineout was a disaster zone. They all played into Scotland's hands.

But the bigger dampener is offered by recent history. It has become a peculiarly Scottish tradition to end the year in an optimistic frame of mind, but for all those high hopes to be shattered in the subsequent Six Nations. Only once since the turn of the century have Scotland begun the tournament with a win.

They will open the 2015 campaign with a trip to Paris in early February. Scotland coach Vern Cotter has happy memories of his visit to the Stade de France in May 2010, for his Clermont Auvergne side's 19-6 French Championship final victory over Perpignan was the making of his reputation as a redeemer, but successive final defeats there in the three previous seasons will add realism to his recollections. Regardless of France's shock loss to Argentina on Saturday evening, the odds are still stacked against Scotland.

And yet, it is still beyond question that Scotland have taken huge strides under Cotter over the past few weeks. Their performances, probably even more than their results, have been a ringing endorsement of his decision to create a style of play that is roughly in line with Scottish traditions. Emotionally, he has pressed the right buttons for his players. Passion is playing its part.

If the memory that lingers from the last Six Nations is of the disconsolate Stuart Hogg walking down the Millennium Stadium tunnel, having being sent off for a gruesome challenge on Dan Biggar, we should wallow in the image of the full-back scampering gleefully up the pitch in Kilmarnock for his side's second try. At 22, Hogg is a little young to be counted among the players who have been rejuvenated over the past few weeks, but he has certainly put a tick in the redemption box.

As, indeed, did all those players who were involved in Scotland's humiliating loss to Tonga in Aberdeen two years ago. That match has cast a long shadow and, for the first 40 minutes at Rugby Park, it seemed the Scottish players were still trapped in it, toiling to impose order, especially around the breakdown, against feisty and unconventional opponents.

At Pittodrie, they had been unable to change and adapt, so the fact they did so here after changing ends 14-12 ahead was comfortably the best aspect of their performance.

"What was important was to be under pressure, but to grind out a win and be able to change our tactics," said Cotter. "At 14-12 it was anybody's game, but I think there was belief within the group at half-time to kick on and get the result. The guys almost increased the engagement and the commitment, the calm and control if you like, and changed the way they played. It's important that comes from guys within the group and I think it's really positive."

Of course, it helped Scotland hugely that Tonga turned over lineout possession six times in the second half. "When those things start to happen it becomes a whole lot easier," said Greig Laidlaw, the captain. But Scotland's second-half transformation also involved playing away from Tonga's strengths and imposing themselves on their opponents. They bossed the game beautifully after the break.

"We knew it was going to be tight," Laidlaw explained. "We were a couple of points up at half-time and probably never played to the best of our abilities. The key message was 'look, we're still in the lead, don't panic, just tighten a few things up'.

"We changed tactics slightly, just to get the ball down there and put pressure on them. Things started to change. The scrum got on top, and the lineout, and we were able to put a lot of pressure on them from there."

Scotland had been hammered in the penalty count in the early stages, allowing Tonga fly-half Latiume Fosita to kick four penalties in the opening half-hour, but Laidlaw explained that the Scottish defence's growing belief that they could cope by fair means eradicated reliance on the foul. Blair Cowan, the man of the match, collected their first try in the 14th minute, Hogg's came in the 33rd, and the second-half haul brought touchdowns by Alex Dunbar, Geoff Cross and Tommy Seymour.

As a general rule, Cotter is pretty good at hiding his emotions, but there was no disguising his pride or his satisfaction at the finish. However, even in that moment of contentment, he was still looking ahead, still looking for where improvements can and must be made.

"I think there are some really positive things and my job now is to try and create other things as well," said the New Zealander. "We want to develop the qualities we have seen over three games. I think the players have made it easy for us.

"They've played well, they've played with heart, they've played with character. The coaching staff, all of us, are happy. They have set standards and that's important, but so is developing the standards.

"I think a lot of those standards are things that they keep within themselves. There is a strength and they will add things as they see fit to make themselves more competitive."