February 2010

Heat Degree Days

Dear Members:

The Sunriver Nature Center monitors daily, monthly and annual information at their weather station. For several years, they have provided us with a yearly summary of this information that includes monthly precipitation and monthly maximum, minimum and average temperature data. I want to share with you this interesting and eye-opening information of the annual weather patterns in our general area.

In comparing the last five years, 2005 was the coldest overall. The comparison is based on a calculation known as Heat Degree Days. The calculation requires daily measurements of maximum and minimum outside air temperatures compared to a base temperature of 65 degrees, which is an estimate of the outside air temperature at which no artificial heating is required. Daily results are added to a running total over the course of a calendar month. 2005 had 8,358 heat degree days compared to 7,457 in 2006, 7,745 in 2007, 8,246 in 2008 and 8,191 in 2009. 2005 also recorded the most rain of the five years with 22.1 inches and 2008 recorded the most snow with 106.1 inches.

In studying the 2009 weather data, a significant fact of interest is that without exception, the minimum temperature reading for any given month (including the summer months) ranged from -22 degrees in December to 32 degrees in July (at or below freezing). On average, the monthly temperature ranged from a low of 15.5 degrees to a high of 83.7 degrees.

You may question the importance of this information, but it supports the fact that heating, regardless of the source, is needed and most likely being used year round in our service area. We often hear that heating is used only during the “winter” months, but with a minimum July temperature of 32 degrees and a minimum August temperature of only 27 degrees, there are undoubtedly many members/customers using their heating systems “to take the chill off” all year long.

If you would like more detailed information about the actual readings taken at the Sunriver Nature Center this past year, please contact our Marketing Department at 541-536-2126. Please remember that while these figures are generally representative of our service area, some adjustments should be taken into consideration for your own specific area.

Bill A. Kopacz
General Manager

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