Weather, wildlife and terrain create special concerns for Glacier Park visitors. So remember:

*Montanans say, "If you don't like the weather, wait five minutes." The adage is especially apt in Glacier, where you may need a No. 15 sunscreen at one bend of the trail and a full set of rain gear at the next. Even in midsummer, prepare for extremes of heat, cold and precipitation.

*If you're recovering from acrophobia, Glacier is a great place to reinforce your resolve. Driving Going-to-the-Sun Road and hiking over the Continental Divide have given more than one park visitor a bout with vertigo.

*Glacier is grizzly country. While the statistics are on your side, you are not totally safe in the back country. The U.S. Park Service dispenses excellent pamphlets on safety tips for hiking and camping in bear habitat.

GETTING THERE: Rtes. 2 and 89 take motorists to Glacier's doorstep. The closest airport sits 20 miles to the southwest in Kalispell, Mont. Amtrak stops just outside the park at West Glacier and East Glacier Park, Mont. Local buses connect with transcontinental lines at Kalispell. For more specific information, contact a travel agent.

RESERVATIONS: Back-country chalets are best reserved as far in advance as possible -- Belton Chalets Inc., Box 188, West Glacier, Mont. 59936, (406) 888-5511.

To book space in one of Glacier's vintage lodges, see a travel agent or contact East Glacier Park, Mont. 59434, (406) 226-5551 (from mid-May to mid-September) and Glacier Park Inc., Greyhound Tower, Station 5510, Phoenix, Ariz. 85077, (602) 248-6000 (from mid-September to mid-May).

WHAT TO DO: For camping equipment rentals and information about guided backpacking or river-rafting tours of Glacier, inquire at Glacier Wilderness Guides, P.O. Box 535, West Glacier, Mont. 59936, (406) 888-5333 (April 15-Oct. 1) or P.O. Box 767, Helena, Mont. 59624, (406) 442-8877 (from Oct. 1-April 15).

Biking the park is possible, though somewhat hazardous on narrow roads during peak traffic. From June 15 through Labor Day, sections of Going-to-the-Sun Road are closed to bicyclists from 11 a.m. to 4 p.m.

Saddle horses and pack stock can be rented from Rocky Mountain Outfitters Inc., 55 Ainley Lane, Kalispell, Mont. 59901, (406) 257-0972.

Boat cruises operate during the summer on Swiftcurrent, Two Medicine, St. Mary and Waterton lakes, as well as Lake McDonald.

Fishing in Glacier lasts from the third Sunday in May to Nov. 30, with a limit of 10 fish daily. The catch may include cutthroat trout, bull trout, burbot, northern pike, whitefish, kolanee salmon, brook trout, mackinaw and rainbow trout.

For those curious about park flora and fauna, the Park Service on both sides of the border offers walks and hikes guided by naturalists and periodic slide shows, demonstrations and movies.

INFORMATION: Glacier guidebooks and maps are available from the Glacier Natural History Association Inc., Glacier National Park, West Glacier, Mont. 59936.