Country Guide

States of the Rocky Mountains Region

For other United States regions click here

It is possible to make a broad distinction between the three northern states of Idaho, Montana, Wyoming, and the rest of the mountainous country of the great Western Cordillera.

In general these northern states are cooler in both winter and summer, have a much longer cold season, and are generally wetter than those farther south. Within this whole region, however, there are so many local variations of temperature and precipitation, because of the range of altitude, that one can find cold spots in the southern parts of the region and some dry areas in the north.

The tables for this region give a good indication of the range of altitude and its effect on temperature in each month. For example, there is no great difference between precipitation and temperatures for Cheyenne in Wyoming and Santa Fé in New Mexico, both of which are above 1,800 m/6,000 ft.

On the other hand, temperatures are very much higher in all months at Phoenix (Arizona) at 330 m/1,083 ft than at Santa Fé.

Much of this region has little precipitation, particularly in the south where large areas of Arizona, New Mexico, Utah, and Colorado are desert or semi-desert with annual precipitation below 300 mm/12 in or even 200 mm/8 in. This is a consequence of the rain shadow of the western mountains in California, which extract much of the moisture from air that comes in from the Pacific. It is also a result of the frequent and persistent anticyclonic weather which prevails in this region.

The table for El Paso, in Texas, has been included with those for this region, for this part of western Texas is mountainous.

The highest-recorded and lowest-recorded temperatures in the tables show that some extremely high and also extremely low temperatures have been recorded at different places in this mountain region: very low temperatures in the north and very high temperatures in the south.

The southern part has the sunniest climate in the United States; both Phoenix and Las Vegas have about eight hours sunshine a day in winter and between twelve and thirteen hours in the summer months. The high summer temperatures in this area are made more bearable by the low humidity and the climate of this whole region is generally healthy. Under extreme conditions, however, both heat stress and cold stress can be experienced.

See also the climatic table for Salt Lake City.

Click on the links below for a detailed look at the United States regions:

USA
Northeastern States (New England)
southern Atlantic States
Northern Interior (Midwest)
Southern Interior and Gulf States
States of the Rocky Mountains Region
States of the Pacific Northwest
California
Alaska
Hawaii