SEATTLE TACOMA INTL AP, WASHINGTON

Period of Record General Climate Summary - Growing Degree Days

Station:(457473) SEATTLE TCOMA WSCMO AP
From Year=1948 To Year=2012
Growing Degree Days for Selected Base Temperature (F)
Base	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.	Annual
40 M	83	110	170	280	474	610	775	774	616	384	171	83	4531
40 S	83	193	364	644	1118	1729	2504	3278	3893	4277	4448	4531	4531
45 M	23	34	61	140	320	460	620	619	466	233	66	21	3063
45 S	23	57	118	258	577	1038	1658	2277	2742	2976	3042	3063	3063
50 M	3	5	12	48	174	311	465	464	317	104	14	3	1920
50 S	3	8	20	68	243	553	1018	1482	1799	1903	1917	1920	1920
55 M	0	0	1	13	71	167	310	309	174	28	1	0	1075
55 S	0	0	1	14	85	253	563	872	1046	1074	1075	1075	1075
60 M	0	0	0	2	22	64	162	160	66	4	0	0	481
60 S	0	0	0	2	25	89	251	411	477	481	481	481	481

Corn Growing Degree Days
50 M	12	27	54	115	226	321	461	462	331	152	38	10	2210
50 S	12	39	93	208	434	755	1216	1678	2009	2161	2199	2210	2210

M = Monthly Data
S - Running sum of monthly data.
Growing 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.
Corn Growing Degree Day units have the limitations that the maximum daily temperatures greater than 86 F are set to 86 F and minimums less than 50 F are set to 50 F.
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