Usually the weather in Colorado is dry and sunny, but like all weather, it can change quickly, so you need to be prepared. The mountains, foothills, desert lands, and high plains can all affect the local climate and make it complex. A good rule of thumb to follow is that the higher the elevation, the lower the temperature – plus an increase in precipitation.
The climate of the Eastern Plains is semi-arid with moderate precipitation and low humidity. This area will usually get from 15 to 20 inches of rain annually. During the day you will find an abundance of sunshine, but at night it will be cool and clear. In the summer you will find temperatures between 95 degrees F and 100 degrees F and in the winter the temperatures can be as low as 0 to -15 degrees F. This area is prone to drought, but when it gets its precipitation it is from thunderstorms, which can be severe. Major snowstorms are frequent as well. The cities closest to the mountains tend to be warmer in the winter because of the Chinook winds. During this time the temperatures can average from 40 degrees F or higher in the winter.
In the foothills and west of the plains, the weather is much less uniform. Even areas that are just a few miles apart can have entirely different weather. Most of the valleys of this area have a semi-arid climate but becomes an alpine climate at higher elevations. In western Colorado, winter is the wettest season and June is the driest month. The precipitation patterns are just the opposite of the patterns in the east. You will find cool summers in the mountains with the high temperatures averaging around 60 to 70 degrees F. Frequent thunderstorms can cause sudden drops in temperatures. At the highest elevations, summer nights can range from cool to cold and there can even be snow in the middle of summer.
A common occurrence in Colorado is the extreme weather, which gives Colorado the distinction of being known as one of the leading states in deaths by lightning. East of the Continental Divide, in the spring and summer thunderstorms are common and hail is a common site in the mountains east of the divide and in the northwest part of the state.
Some of the biggest hail storms in North America occur on the Eastern Plains, which is also part of Tornado Alley and produce some of the deadliest U.S. tornados. The plains are also susceptible to floods.