SAINT HELENA, CALIFORNIA

Period of Record General Climate Summary - Heating Degree Days

Station:(047643) SAINT HELENA
From Year=1931 To Year=2006
Heating Degree Days for Selected Base Temperature (F)
Base	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.	Annual
65	572	421	375	246	118	30	3	4	25	133	353	549	2829
60	418	281	228	124	39	4	0	0	3	45	211	395	1747
57	326	201	150	69	15	1	0	0	1	19	137	303	1222
55	266	151	106	43	7	0	0	0	0	9	96	245	924
50	134	56	31	8	1	0	0	0	0	1	28	118	377

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