Simplify the following text for a Grade 7 native English-speaking person.
Original: A main climatic division in Colorado occurs between the Rocky Mountains on the west and the plains on the east with the foothills forming a transitional zone between the two . Northeast , east , and southeast Colorado are mostly the high plains , while Northern Colorado is a mix of high plains , foothills , and mountains .
Simplified: There is a change in climate in Colorado between the Rocky Mountains on the west and the plains on the east with the foothills .