The sunshine across New Mexico occurs 75 percent of the year. New Mexico spans approximately five degrees of longitude and three degrees of latitude. The northern part of the state has 100 frost free days.
Dry air make the relative humidity low preventing either extreme from being two unpleasant.
New Mexico climate has changed throughout the ages. From the Miocene to the present a gradual drying trend continued and the fossil plants of Miocene period and later are very similar to the current vegetation types. The current vegetation in the western United States including New Mexico. The climatic trend resulted from a variety of factors, including the uplift of the Sierran-Cascade axis, the Rocky Mountains, and the Sierra Madre of Mexico. The area of New Mexico, and the southwestern United States, lies in a double rain shadow that came into existence during the late Tertiary.