High Plains
Moving from east to west across Colorado, the first land type is a continuation of the Great Plains, a flat to gently sloping grassland punctuated by occasional bluffs and hills. The northeastern part of the state receives the highest temperatures, occasionally exceeding 115 degrees Fahrenheit. The plains are relatively dry, with 75 percent of the rain that does fall occurring between April and September, during the growing season. High winds during dry periods cause occasional dust storms, especially in the southeast.
Foothills
Where the western edge of the high plains meets the eastern edge of the Rocky Mountains, the climate changes noticeably. In the foothills, wind speed tends to be lower than on the plains, except for occasional severe windstorms. There is less seasonal temperature variation, with warmer winters and cooler summers. Rainfall increases along with elevation in the foothills. Air movement from mountain valleys keeps winter temperatures warmer than the altitude might suggest.
Mountains
Climate in the mountains of Colorado is widely variable, with extremely cold temperatures on the highest peaks, averaging 32 degrees or less over the course of a year, with lows reaching 50 degrees below zero in the winter and highs occasionally touching 90 degrees on summer days, with cool summer nights. Severe thunderstorms and blizzards are common on the eastern slopes, but less likely on the western slopes.
High Mesa
The plateau country of far western Colorado receives most of its rain in the winter, the opposite of the rainfall pattern in the east. High pastures offer quality forage for livestock or hay production, while sheltered valleys grow vegetables, fruit trees and grain. Snow pack and underground water supply irrigation for agriculture in these areas. Some of these valleys have growing seasons of up to 190 days, considerably longer than other areas of the state.