Weather events should not be confused with climate.

It has been said that the difference between weather and climate is that climate is what we expect and weather is what we get. Meteorologists consider climate to be the long term manifestation of either the condition or the course of the weather, and climate is defined by the statistical collection of weather conditions for a given region during a specified interval of time, usually several decades (see the Glossary of Meteorology, American Meteorological Society, 1986, or National Climate Data Center U.S. Climate Normals for more details). Given this definition of climate and its distinction from weather, a single weather event, or even a spell of unusual weather, may be unprecedented and still well within the bounds of "normal" climate variability. Weather and climate records in the U.S. have only been collected for a little over 100 years, which is too short a period to determine whether or not the events of this winter were so far outside the range of normal variability as to be caused by human intervention in the earth's climate. Such an event or group of events, by itself, is not an indication of a climatic trend, even if many years from now hindsight indicates that it was part of such a trend.