Assuming I never set foot into the outside world, and I never had access to either a window, a radio or a television, I still reckon I could roughly gauge what the weather was doing by the sort of problems my clients come in with at certain times of the year.

I'd say that the chief culprit is temperature.
You might think that moisture would be the biggest problem, but then woodwind instruments are designed to deal with moisture and it really only becomes a problem when it's associated with a change in temperature.
A typical call from a client as Autumn turns to Winter will be about a problem with a sticking key - particularly if the instrument is a modern plastic clarinet. These instruments are very prone to shifts in temperature, and can swing from being rattley and loose on a hot day to being stiff and slow on a cold day - and usually all that's required is an adjustment of the point screws.

Excess moisture too can throw up a few problems as the ambient air temperature drops, and during the winter even the driest of players can find themselves having to deal with condensation flying off the keys onto their hands.

So when a client called in about a problem with the tuning on a specific note on his oboe I had it in mind that it was probably going to be down to a sticky key somewhere, most likely connected with the recent cold snap.
The problem itself was curious enough to be worth mentioning, I don't think I've ever come across anything quite like it.
The note concerned was lower/middle F.
What happened was that you could sometimes play the F just fine, and yet at other times it was dreadfully flat and muted. Even more extraordinary was that the note often started off good and then deteriorated while you were playing it. It actually started to flatten off while you were blowing, and no amount of embouchure tweaking could prevent it.

So I was dealing with that very worst of problems - an intermittent tuning fault.
My first instinct was to examine the instrument for leaks. I found a couple of very minor leaks and duly corrected them - but to no avail, I hadn't made any difference at all.
With a rock-solid seal on the pads it surely had to be an action problem, and my first thought was that it might be what I like to call 'operator error'...which translates roughly to a player pressing keys when they shouldn't be pressed - but this is really only applicable to beginners, and not a regular player with an expensive instrument. Nonetheless it was worth a mention, but it still didn't seem to be the cause of the problem - especially as we both had the same tuning problem with the F.

I then considered the environmental issues and asked about where and how the instrument was stored.
More often than not clients will say that they keep the instrument indoors, and that it doesn't spend much time outside (in the boot of a car, for example) - but this tends to overlook the fact that most people have their heating switched off during the wee small hours...and if it's minus 5 outside then whilst it won't be anywhere near as cold indoors during the night it will still mean that the temperature in the house drops below the norm. Having just had a particularly cold snap over here I was expecting quite a few instruments to have succumbed to a spot of contraction.
With this in mind I examined the oboe from top to bottom - and allowed myself a discrete 'woohoo' when I spotted a pillar just ever so slightly out of alignment.
This is a perfect example of how environmental conditions can play havoc with a woodwind instrument; a drop in temperature causes shrinkage, a rise causes expansion, and between the two poles the poor old instrument ends up with loose pillars, which can lead to all kinds of unpredictable and intermittent problems. This is why some clarinets have little plates alongside certain pillars, and these plates are locked in position with a small screw. It's this plate that helps prevent the pillars becoming loose and turning under the tension of the springs.
And so I duly set about realigning and tightening the offending pillar, fully confident that I'd discovered the problem.

But I hadn't...the F still played out of tune sometimes.

I'd been through my armoury of techniques...I'd even given the speaker key vents a bit of a clean, and popped a couple of drops of oil here and there (well, ya never know), but nothing seemed to solve the problem.
I have to admit I was at a loss and wasn't far off telling the client to take the oboe home and see if the problem doesn't sort itself out in a week or two (surprisingly enough, this sometimes works!), when I noticed something...something very small.
I'd been holding the oboe in my hands, and whilst talking to the client I'd been idly turning the top joint in the mid tenon socket...and suddenly I felt just the faintest 'knock'.
I've always said that the most important aspect of repairing is feel, and what I was feeling didn't feel right.
Oboes are quite delicate instruments, and so in order to ensure that the lower joint doesn't split asunder every time you push the top joint into the mid tenon socket, the socket is lined with a metal sleeve - over which another metal ring is fitted, typically with a couple of pillars fitted to it.
Now, a lightly greased corked tenon joint sliding into a metal lined socket should give a very smooth action - but as I turned the upper joint back and forth in the socket I could feel it just faintly catch and give...as though something was loose.
Sure enough, as I looked closely at the socket I could see that every now and again the inner sleeve would move just fractionally. It really was just fractionally, you could barely see it and yet you could definitely feel it once you knew what you were looking for.

It explained the problem perfectly; every so often your fingers would apply just the right pressure in just the right place to place stress on the tenon joint, and when this happened the inner sleeve lining would rock slightly and start to leak...and the note would flatten off. With one of the note's tone hole being just below the leaking joint it was sure to have an impact.
But how did it come to leak in the first place?
Temperature.
The sleeve is glued in, usually with shellac (so that it can be removed, if required, with the application of a little heat), and shellac is a fairly brittle kind of glue when it's set. With a sharp drop in temperature over the last couple of weeks it's highly likely that the tenon sleeve shrank further and faster than the surrounding wood and cracked the shellac seal.
I removed the outer sleeve ring and with the aid of a little gentle topical heat ran some Carnuba wax into the inner sleeve joint - this is a particularly stiff wax that will hold the joint as well as shellac, but will cope better with any expansion and contraction.