Climate
Extremes of weather and climate prevail at Craters of the Moon across seasons and elevations. From the foothills of the Pioneer Mountains on the northern end of the monument to the Snake River on the south, weather conditions vary significantly. As elevation decreases from north to south, temperatures increase and precipitation decreases. Average annual precipitation ranges from 16 inches at the monument Visitor Center to just under 10 inches near the Snake River at Minidoka Dam. In February, average snow depth ranges from 26 inches at the north end of the monument to just 2 inches at the south end. Intense summer sun bakes the black lava, generating surface temperatures of 170 degrees Fahrenheit and air temperatures in the 90s. Drying winds are a daily occurrence, especially in the afternoon, and may reach 15 to 30 miles per hour. In June, July, and August, the average monthly precipitation is less than two inches. Winter transforms Craters of the Moon into a dramatic landscape of rugged black lava and soft white snow. Fall and spring are milder, with unsettled weather. Despite harsh conditions, delicate wildflowers burst to life in May or June against the more monochromatic background of the cinder slopes: pink monkeyflowers, yellow dwarf buckwheats, white bitterroots, and many others. No matter what the season or the weather, the wide open desert sky at Craters of the Moon offers unobstructed views of spectacular cloud formations, sunrises, sunsets, moonscapes, and stars.
Flora and fauna
Despite the seemingly barren landscape the park supports a rich diversity of life including more than 660 types of plants and over 280 animal species. While searing lava flows that initially destroyed everything in their path today protect the last refuges of intact sagebrush steppe communities on the Snake River Plain. These islands of vegetation, known as kipukas, provide important examples of what is "natural".
Animals seen most frequently in the park are birds and some rodents. The changing weather and seasons play a large role in determining which animals are active at any given time. Most desert animals are nocturnal, or mainly active at night, and include woodrats also called packrats, skunks, foxes, bobcats, mountain lions, bats, nighthawks, owls, and most other small desert rodents. Animals that are most active at dawn and dusk, when temperatures are cooler than mid-day, are called crepuscular. The subdued morning and evening light helps make them less visible to predators, but is bright enough to allow them to locate food. Crepuscular animals in the park include mule deer, coyotes, porcupines, mountain cottontails, jackrabbits, and many songbirds. The park's diurnal animals are those that are most active during the day, and include ground squirrels, marmots, chipmunks, lizards, snakes, hawks, and eagles. Animals that are unique to Craters of the Moon and the surrounding area include subspecies of Great Basin pocket mouse, pika, yellow pine chipmunk, and yellow-bellied marmot are found nowhere else in the world. Lava tube beetles and many other cave animals are found only in the lava tubes of eastern Idaho.
To date there have been over 212 species of birds sighted on or over the monument and preserve. Many of these are rocky area or shrubland specialists seen in large numbers in only a few other places in the country. Most are found in the areas of the park where water occurs; many small ponds and lakes formed by spring rains and snow melt provide temporary homes for a surprising number of waterbirds, such as ducks, geese, shorebirds, herons, and gulls. Even swans are sighted regularly during the spring migration north to Canada. A few small riparian areas and aspen clumps provide shelter for warblers, vireos, catbirds, orioles, woodpeckers, and more. Small marshes on the northern edge of the lava flow attract blackbirds, wrens, and herons. The park's shrublands supports birds such as Brewer's Sparrows, Sage Sparrows, Sage Thrasher, and Sage Grouse. Limber pine, rocky mountain, and Utah juniper stands growing in cinder gardens and kipuka areas offer habitat to woodpeckers, flycatchers, chickadees, nuthatches, warblers, sparrows, and finches. These patches of trees in the midst of a vast sea of shrublands and barren lava flows are a beacon to many migrating birds, such as warblers, sparrows, and flycatchers, which reside here for brief periods in the spring and fall. The seemingly barren lava flows provide shelter for Mountain Bluebirds, Violet-green Swallows, and Rock Wrens. During the long, cold winters that are characterized by blowing snow and temperatures well below freezing, birds are still found at Craters of the Moon. Ravens, nutcrackers, and chickadees live here all year. Mountain and arctic birds that stay for the winter include Black and Gray Crowned Rosy-finches, Rough-legged Hawks, Northern Shrikes, Snow Buntings, and in some years even Snowy Owls or Gyrfalcons.
History
The park was created in 1924 by President Calvin Coolidge, who at the time described it as "a weird and scenic landscape peculiar to itself". The area was designated the Craters of the Moon Wilderness in 1970 by Congress, the first such designation within the National Park Service.
Landscape
Over the past 15,000 years, lava eruptions created a rugged but scenic landscape that has forced animals and plants to adapt, and people to endure, detour, or ponder. Located on the Snake River Plain, a volcanic terrain spanning southern Idaho, the Monument and Preserve encompasses the Great Rift volcanic rift zone. In places, this plain is 60 miles wide, with basalt lava deposits over 10,000 feet deep in some locations. Eruptions 2,000 years ago at the Craters of the Moon and the Wapi lava fields are among the most recent volcanic activity to take place anywhere in this immense geographic area. Features visible today include an isolated landscape filled with such features as cinder cones, spatter cones, lava tubes, and several types of lava flows.