545 hectares (1,347 acres).
Elevation
The park is about 1,290 meters (4,250 feet) above sea level. The Tower rises another 264 meters (867 feet) to the top.
Climate
Summer temperatures cover a wide range from daily highs of 29°C (83°F) to lows of 10°C (50°F). Winter temperatures plunge below freezing for long periods of time. Spring arrives usually sometime in April, but the temperature drops quickly at night and stays cold during the day if it’s cloudy. About the end of September, fall begins, and with it the golden color of changing cottonwood leaves along the Belle Fourche River.
Best times to visit
Spring is short in the Rocky Mountain West and can be a time of violent shifts in weather: summerlike days alternating with cold, always the possibility of late heavy snowfalls, and no inbetweens. These extremes seem to be tempered somewhat at Devils Tower, and the fun of watching deer can more than make up for any inconvenience due to the weather. Whitetail deer, followed by their spotted fawns, are rubbing off winter coats. They seem to be browsing the park hungrily everywhere you look.
Summer heat, because of elevation and dry air, radiates quickly but never becomes stifling. Winds are strong and steady and there is always a danger of exposure for those unprepared for sudden thunder and lightning storms, or for the sudden cooling after sunset. Most visits to Devils Tower are made in the summer when the surrounding rangelands are green and the sparkling watercourses invite refreshment under shade of cottonwoods.
Early fall, just as the range begins to brown, is perhaps a perfect time to be at Devils Tower. The park is uncrowded after Labor Day. Protected meadows are still green. Animals are in their prime and ready for the rigors of winter. The faint odor of decaying vegetation and the foretaste of winter on a particularly bracing chill wind—these are the pleasures of a long Wyoming fall.
Winter brings an air of enforced isolation to Devils Tower. Heavy snows and frequent blizzard conditions on the highways discourage most travelers. A rare treat awaits those who do come here in winter, however. Bald eagles migrate down from the north. You might see them wheeling in pairs over an otherwise frozen landscape, or making a feast of carrion on the ground.