Problems with humidity can lead to heartbreak for the classical (or other) guitarist. Excessive humidity or dryness can ruin an instrument probably quicker than you think.

You must always be aware of what conditions you are leaving your instrument, whether inside a guitar case or within a room or in the open. They should NEVER be left in the sun for any length of time.

When guitars are built they are usually in an environment where the relative humidity of the room is kept constant, roughly around 50%.

To be safe you ideally should keep your instrument around this mark though they are generally regarded as safe between 40%-70% as the upper and lower margins. Below or above this can be drastic for your instrument!

An interesting example of anecdotal evidence of problems with humidity I've heard is with Ramirez guitars.

Because they're made in Spain where the humidity is often above the 50% mark and are shipped to areas where the humidity is much lower with dry winter conditions, they can easily develop cracks and slits throughout the guitar.

Having made an investment for such a beautiful guitar youd be mad not to invest in a relatively cheap system for keeping the humidity of your guitar constant, like a guitar humidifier case for example.

The damage caused by too much humidity or of drying out your instrument can range from cracks, splits and shrinkage to warping and even snapping of the wood.

There are many things you can do to prevent problems from the start. You know the old saying "an ounce of prevention is worth a pound of cure."

I would recommend keeping your house, or wherever you keep your instrument, at a constant temperature and humidity all year round.

Next I would get a humidifier for my guitar case, whether one sold commercially which releases moisture slowly and attaches to the inside of your case, or a home-made one which could consist of a wet cloth (be careful not to let it touch your instrument as it may damage the wood).

Another thing to invest in is a "hygrometer", which is an instrument that will keep track of humidity, or lack of it in your guitar case. As mentioned above, some guitar cases are made with these things as standard.

If you follow these few simple rules and keep an eye out for changes in temperature and humidity conditions it shouldn't be hard to keep your instrument in good order.