Historical Divisional Temperature and Precipitation records

Climate Divisions
New England weather is as diverse as it is variable and has many regions with significantly different climates.  Since weather patterns do not obey political boundaries, climate divisions have been established within each state to more accurately characterize regional weather.  For example, coastal regions tend to be warmer and have more precipitation than inland regions, which is an important trait that would be lost if all the state's data were averaged into a single value. Therefore, the National Oceanographic and Atmospheric Administration's National Climatic Data Center (NOAA-NCDC) has organized New England temperature and precipitation data by climate division. However, the average temperature and precipitation for the entire New England Region is also presented here to give an overview of how the climate of the entire region has changed since 1895.

Climate Data
The data used to generate graphs are from the National Climatic Data Center. The divisional data are averages of measurements taken at stations within each division.  The temperature timeseries are the average annual or seasonal values for each three-month period (Dec-Feb = Winter; Mar-May = Spring; Jun-Aug = Summer; Sept-Nov = Fall).  To compute the average temperature, the daily averages (defined as the average of the maximum and minimum temperatures [(max + min)/2]), are averaged for each period. The divisional timeseries of precipitation are annual or seasonal values, which represent the total precipitation (rain-equivalent) of the region for that period.  The series for the New England region is comprised of areally weighted values (the larger divisions are given more "weight" in the average).  Data has been adjusted to correct for varying observational times as described on the NCDC website .  In addition, digitized data from each division is unavailable from 1895-1930, so the divisional values for this period were estimated using regression techniques from regional values.  New England was divided into two regions, Northern New England (Maine, New Hampshire, and Vermont) and Southern New England (Connecticut, Massachusetts, and Rhode Island); The values from these two regions were used to estimate the divisional values from 1895-1930 (For more information see "A Historical Perspective of U.S. Climate Divisions" N. Guttman, NCDC, Bulletin of the American Meteorological Society: Vol. 77, No. 2, pp. 293304). Care must be taken in interpreting pre-1930 data, which has also influenced trends over time.  The data can be accessed at the NOAA-CIRES Climate Diagnostics Center

National Climatic Data Center -  http://lwf.ncdc.noaa.gov/oa/ncdc.html

Access the Divisional Data -  http://www.cdc.noaa.gov/Timeseries/