SEATTLE TACOMA INTL AP, WASHINGTON

Period of Record General Climate Summary - Cooling Degree Days

Station:(457473) SEATTLE TCOMA WSCMO AP
From Year=1948 To Year=2012
Cooling Degree Days for Selected Base Temperature (F)
Base	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.	Annual
55	0	0	1	13	71	167	310	309	174	28	1	0	1075
57	0	0	0	7	46	118	249	248	124	14	0	0	807
60	0	0	0	2	22	64	162	160	66	4	0	0	481
65	0	0	0	0	5	20	60	55	16	0	0	0	157
70	0	0	0	0	1	5	17	13	2	0	0	0	38

Cooling Degree Day units are computed as the difference between the daily average temperature and the base temperature. (Daily Ave. Temp. - Base Temp.) One unit is accumulated for each degree Fahrenheit the average temperature is above the base temperature. Negative numbers are discarded. Example: If the days high temperature was 95 and the low temperature was 51, the base 60 heating degree day units is ((95 + 51) / 2) - 60 = 13. This is done for each day of the month and summed.
Table updated on Oct 31, 2012
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