SPRING - April / May / June
Spring comes a bit late to the high desert of southern Idaho. At Craters of the Moon, winter snowpack may last into early May and often the loop road is not open for use until mid-April. April and May can still see snow storms that temporarily close the loop drive, snow on many of the trails, and closure of the lava tubes or caves due to hazardous ice. Temperatures can vary from warm to cold during the daytime to cold during the night. Camping facilities are limited at this time and services limited. From mid to late-June the wildflower bloom at the monument is at its peak. Longer hikes into the wilderness are recommended during this period of moderate temperatures.
SUMMER - July / August
Summers can be described as warm to hot during the day with rapid cooling during the evening that leads to chilly nights. Trail hiking is best planned during the morning hours with a visit to the cool inside of a lava tube recommended for the afternoons. Visitation peaks during this period, but most attractions can still be enjoyed and solitude is still available to those who seek it. The campground generally fills by late evening on most nights.
FALL - September / October
Temperatures cool down during this period and the lack of wind can make this some of the most ideal weather during the entire year. Programs are no longer presented, but the crowds are gone as well making it an ideal time to see the monument on your own. This is a good time for backpacking into the wilderness area of the monument. Camp sites are easy to find and water and facilities in the campground are available into October depending on the low temperatures. Aspen in the mountain areas to the north of the monument take on autumn colors during this time.
WINTER - November / December / January / February / March
Winter covers a long period at this latitude and altitude. The loop road usually closes by mid-November and then cross-country ski track is prepared as soon as a good snow base forms. Snowshoeing is becoming more popular in the monument and a limited number of special winter ecology walks are given in January and February. Winter temperatures can dip well into the minus 30 degree levels and blizzard conditions can occur during any winter month. The visitor center is closed on winter holidays.