As winter approaches and the humidity levels go lower, my strat develops fret sprout. I think what happens is that the neck (maple) seems to shrink as it dries out and the fret wires become exposed along the edge. In the summer, when humidity increases, the opposite happens and it goes back to “normal”.
I’ve considered buying a file to deal with it, wondering if anyone else on the forum has attempted this and has advice?
Get a humidifier or two, that’ll solve your problem. I have a humidifier running non-stop during heating seasons which does a great job at keeping my guitars from drying out. If you store your guitars in cases there are also plenty humidification solutions for that. (I use D’Addario Humidipaks)
You can get fret files from Amazon or Stewmac, it’s not very difficult but be real careful because it’s easy to damage the fretboard if it’s your first time.
You say that in the summer your guitar goes back to normal. That means if you file your frets in the winter, in the summer they’ll be too short. Don’t file them. As Ivan says, get some form of humidification going.
I have done fret filing before and it can be done if you are careful. But it is a pain to do unless you have a full set of tools. It is also not the problem.
The real problem is the humidity and as Ivan(@SS7) mentions, you are better off solving the problem with a humidifier than permanently altering you guitar.
If you like your guitars out, like I do, you need to humidify the whole space, so you need a large enough humidifier. If your water is hard, I would recommend and evaporative one to avoid deposits on furniture and guitars.
Other options are to keep the guitar in a case and humidify that. Lots of products available, but people also take a moist sponge and put it in a soap container with holes drilled in it.
Some also have a small closet they can keep guitars in and just humidify that with a smaller humidifier or even damp towels hung up.
I have read that to rehydrate a dry guitar, some Luthiers will put it in a plastic garbage bag along with some moisture source (as long as you don’t get the guitar soaked) and let it sit a few weeks.
Some type of humidity meter is a good idea.
I hope that helps. There is a lot of information online about how to care for your guitar. I live in dry Denver Colorado and do pretty well with a RH 30-35% at 70-75F, which is less than recommended, but no issues yet and would require a big effort to do better.