Common Sense Climate Index
Example - New York City
The composite climate index is the average of several component indices shown by the line graphs. The component indices have a high degree of similarity, which is expected because at present all of the components are based on temperature.
The Climate Index for New York City does not have an apparent trend during the last 50 years, although there was an increase during the first half of the twentieth century. The Index has been relatively high in the past decade, but it had similar values in the 1950's. An Index greater than 1 occurred in 1991, but the next year the Index was negative (less than the 1951-1980 average).
For more info, see NYC Means and Extremes.

