[Source: NOAA Climate Prediction Center, http://www.cpc.ncep.noaa.gov/
These data sets contain weekly and monthly population weighted cooling degree day data for each state, each region (9), and for the contiguous U.S. A mean daily temperature (average of the daily maximum and minimum temperatures) of 65 degrees F is the base for cooling degree day computations. Each stations record contains ... the total from the summation of daily values, departure from the normal (based on 1951-1980), departure from last year's total, accumulated total from the beginning of the season, departure from the accumulated season normal and percentage, and departure from last year's accumulated season normal and percentage. The data are collected from ground stations throughout the U.S. The data are displayed in tabular form. CAC only keeps the previous week's and month's data on-line, but you can contact NOAA's National Climatic Data Center for the historical data.
These cooling degree days are estimated for state climate divisions and then population weighted to more accurately reflect temperature related energy consumption at the state, regional, and national levels. Temperature data, however, are not readily available on a daily basis for climate divisions. Therefore, equations which relate the historical temperature of state climate divisions to nearby weather stations (which have temperature data accessible daily) are used to estimate climate division temperatures. There are 198 weather stations nationwide used in the equations. Between one and four weather stations are used for each equation. There are 12 monthly equations for each of the 344 state climate divisions in the 48 contiguous states. For example, the equation for estimating the average daily temperature (F) in the Northern Climatic Division (NJCD1) in New Jersey during December uses the average daily temperature at the LaGuardia Airport, New York weather station (LGA) for a particular day. Once the daily temperature for each climate division has been estimated for the period of interest, cooling degree days are calculated. The climate division cooling degree days are then weighted according to their proportion of the state's population (1980 Census) they contain.
Using the state weights determined in this manner, regional degree days are calculated in proportion to populations in the respective states. Regional divisions are weighted by the same procedure in the computation of national degree days. The previously described estimation and weighting procedure is used in computing current degree days and last year's degree days. Normal degree days for climatic divisions are modified slightly and are derived from normal degree days for stations. The comparisons against the previous year are all estimated and population weighted using this procedure.
The gas, oil, and electric home cooling customer weighted degree days are computed on a regional and national basis by a similar procedure by weighting the states in regions and the regions in the country by the number of residential customers cooling with electric air conditioning (1980 Census).
All data sets are available via World Wide Web from the NOAA/CPC Home
Link to: "cooling customer weighted degree days are computed on a regional and national basis by a similar procedure by weighting the states in regions and the regions in the country by the number of residential customers cooling with electric air conditioning (1980 Census). All data sets are available via World Wide Web from the NOAA/CPC Home Page. Link to: http://www.cpc.ncep.noaa.gov/