SEATTLE URBAN SITE, WASHINGTON

Period of Record General Climate Summary - Heating Degree Days

Station:(457458) SEATTLE URBAN SITE
From Year=1972 To Year=1998
Heating Degree Days for Selected Base Temperature (F)
Base	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.	Annual
65	715	586	546	407	255	123	41	36	119	352	569	718	4466
60	560	445	391	259	123	28	2	2	31	201	419	563	3024
57	467	360	298	176	61	6	0	0	8	121	329	470	2297
55	405	304	237	126	31	2	0	0	2	78	271	408	1864
50	254	170	100	32	2	0	0	0	0	15	140	257	970

Heating Degree Day units are computed as the difference between the base temperature and the daily average temperature. (Base Temp. - Daily Ave. Temp.) One unit is accumulated for each degree Fahrenheit the average temperature is below the base temperature. Negative numbers are discarded. Example: If the days high temperature was 65 and the low temperature was 31, the base 50 heating degree day units is 50 - ((65 + 31) / 2) = 2. This is done for each day of the month and summed.
Table updated on Jul 28, 2006
Months with 5 or more missing days are not considered
Years with 1 or more missing months are not considered

Western Regional Climate Center, wrcc@dri.edu