“Dressed to the nines” is a shipping term from back when ships had 3 masts each with 3 primary yards.

Usually not all in use – hence “the whole nine yards”. Therefore, on very formal occasions or to celebrate a victory the ship would be in full sail or “dressed to the nines”.

‘cloud nine’

Based on actual terminology used by the U.S. Weather Bureau. Clouds are divided into classes and each class is divided into nine types.

‘Cloud nine’ is the cumulonimbus cloud that you often see building up in the sky in a hot summer afternoon.

It may reach 30,000 to 40,000 feet, so if one is up on ‘cloud nine,’ one is high indeed.

Could that be it? Also, when you get to 10 you’ve run the race already…but dressing to nines, and cloud nine…that’s pretty much on top! I’ll go with that instinctual answer. Threes.

altho’ they all mention nine as significant.

Cloud nine seems to be from a numbering system used a while ago; the 9th being the highest in elevation. Dressed to the nines has been answered I think. And for the answer to “whole nine yards” you probably want to look it up using kilt and

the poem of Andrew MacTavish and Mary Margaret MacDuff.

Ammunition belts for airplanes (world war II) came in nine yard belts. So when the pilots would strafe a target and they got all their rounds off on the target they would say that they gave it “the whole nine yards”

Check out this article it’s all about your question and ALL the possible origins for the whole nine yards.

http://www.worldwidewords.org/articles/nineyards.htm