USDA Forest Service

North Central Research Station

Temperatures

Daily maximum and minimum temperature data from the National Climate Data Center's (NCDC) TD-3200 file, as corrected by NCDC's Validated Historical Daily Data project, was used to develop maps of average monthly maximum and minimum temperatures and occurrences of "extreme" maximum and minimum temperatures.

Average monthly maximum and minimum temperatures were computed from observed daily maximum and minimum temperature data at each observation site across the North-central and Northeastern US over the period 1950-1993.  A kriging interpolation procedure was used to provide data at locations between observation sites.  Because the kriging process does not explicitly take into account small-scale factors that can influence measured temperatures at the surface, the temperature maps should only be used to provide an indication of the broad, regional-scale variation.  The maps should not be used as tools to identify monthly average maximum and minimum temperatures at specific points on the maps.

 
Average Temperature
Maximum Minimum   Maximum Minimum
 Jan  January Average Maximum Temperature January Average Minimum Temperature  Jul  July Average Maximum Temperature July Average Minimum Temperature
 Feb  February Average Maximum Temperature February Average Minimum Temperature  Aug  August Average Maximum Temperature August Average Minimum Temperature
 Mar  March Average Maximum Temperature March Average Minimum Temperature  Sep  September Average Maximum Temperature September Average Minimum Temperature
 Apr  April Average Maximum Temperature April Average Minimum Temperature  Oct  October Average Maximum Temperature October Average Minimum Temperature
 May  May Average Maximum Temperature May Average Minimum Temperature  Nov  November Average Maximum Temperature November Average Minimum Temperature
 Jun  June Average Maximum Temperature June Average Minimum Temperature  Dec  December Average Maximum Temperature December Average Minimum Temperature
Note:  The color scale for each image is set to increase the contrast for that image.  Because of this, one must take care to consider the individual color scales when comparing two images.
 

There are many ways to define "extreme" temperature events.  For this Disturbance Climatology system, four different extreme temperature events were defined as follows:

  • a daily episode where maximum surface temperatures were at least 20°F above the climatic average maximum temperature for that day.
  • a daily episode where maximum surface temperatures were at least 20°F below the climatic average maximum temperature for that day.
  • a daily episode where minimum surface temperatures were at least 20°F above the climatic average minimum temperature for that day.
  • a daily episode where minimum surface temperatures were at least 20°F below the climatic average minimum temperature for that day.

Observed daily maximum and minimum temperature data at each observation site across the North-central and Northeastern US over the period 1950-1993 were analyzed to determine the total number of each of these extreme events that occurred in each month over the 44-year period.  As with the monthly average maximum and minimum temperature maps, a kriging interpolation scheme was used to generate the maps of extreme temperature occurrence over the entire North-central and Northeastern US.  The extreme temperature occurrence maps should only be used to provide a broad, regional-scale indication of where extreme temperature events tend to occur in each month.

 
Extreme Temperature
Maximum Minimum
Events
above
Threshold		 Events
below
Threshold		 Events
above
Threshold		 Events
below
Threshold
 

For more information:

USDA Forest Service - North Central Research Station
Last Modified: January 26, 2005