AS YOU tour the fall colors, remember that the weather is changing as well as the leaves. While Mother Nature is getting bare-bark naked, we have to be bundling up. There is special danger this time of year because people don't realize there is danger. While the sun may be bright and warm, the air temperature can get low enough, especially with a little wind, to trigger hypothermia if you get wet.

Hypothermia is loss of body heat. It causes shaking and slurred speech in early stages, confusion and loss of coordination later and, if not quickly and properly treated, death.

While hiking, you can get wet from perspiration or rainfall, and if you're boating, there's the extra chance of a dunking.

The best cure is prevention. Dress properly and carry extra clothing, warm liquids and firestarters in a waterproof container.

The best clothing is wool or polypropylene. The worst is cotton or a cotton blend. Wool holds some body heat even when it is wet. Polypropylene dries very quickly and keeps you warm as long as you move around. Cotton, on the other hand, or cotton and synthetic blends aerate you, accelerating heat loss.

Windbreakers help fight hypothermia, and layering is more effective than wearing a single heavy outer garment. Perhaps the most useful single item of clothing is a hat. Your bare head acts just like a chimney.

For whitewater trips at this cold-water, cool-air time of year, wear a neoprene rubber wet suit. Dive shops and many rafting outfitters rent them.

Whatever type of small boat you choose for a fall colors tour, your most important piece of gear is a good lifejacket. It will not only keep you afloat if you fall in, it will provide some extra insulation against the cold.

Outdoor stores in the area have books on preventing and treating hypothermia. If you spend much time outdoors for any reason, get one and heed its advice. It could save your life, or help you save someone else's.