03 Sep, 17
by Dale
in current events
0
0

how hot?

This weekend, the San Francisco Bay Area is having an historic heat wave. In the City, temperatures reached 106°F, while out here in Concord, we have seen 116°. On September 2, Concord was hotter than Bangkok and Death Valley! Since Weather Underground has great data, I thought I’d take a look at the trend.

First, here at our house: We have a weather station in the backyard that reports data to Weather Underground. It tells us the following about the period from Memorial Day through today this year:

96° – the average maximum temperature
77° – the average of the 24-hour mean temperatures
56 – the number days where the maximum temperature exceeded 95°
33 – the number days where the maximum temperature exceeded 100°
24 – the number of days where the maximum temperature exceeded 105°

Yes, it’s been hot, but has this year been hotter than others? I looked at the historical data for Buchanan Airfield (KCCR) for the past 30 years and I came up with a few interesting charts. (Click on these to see a bigger version.) Traditionally, summer runs from Memorial Day through Labor Day: that’s the period covered in these graphs.

The “mean temperature”, which is the overall temperature in a day, was at an all-time high this year. From 1988-2014, the range was 69° to 72°. 2017 has been higher than that: the average mean temperature has been 75°

Things become a little more dramatic when you look at the average maximum temperature. The trend since 2011 is pretty striking.

Finally, when you look at the number of hot days each year, we see the same alarming trend.

I think it’s fair to say that, here in Concord, CA, this has been the hottest summer in 30 years.

Here are the numbers I used today.

YEAR	# of days	average max temp	average 24-hour temp	average min temp	days above 95°	days above 100°	days above 105°
1988	99	85	72	58	22	5	1
1989	99	83	70	57	8	3	0
1990	99	84	71	58	13	5	0
1991	99	82	69	56	7	1	2
1992	106	85	72	58	10	1	0
1993	99	85	72	59	16	5	1
1994	99	86	72	58	13	2	0
1995	99	84	72	60	16	5	0
1996	99	87	73	59	26	10	0
1997	99	86	73	61	11	3	0
1998	106	84	71	59	23	12	2
1999	99	82	69	55	12	5	1
2000	74*	84	71	58	16	5	2
2001	99	86	71	57	23	6	2
2002	99	85	71	57	14	7	2
2003	99	87	72	58	22	4	0
2004	99	86	72	59	14	4	0
2005	99	86	71	57	17	3	0
2006	99	87	72	58	24	12	6
2007	99	86	72	57	17	6	0
2008	99	87	72	57	19	10	4
2009	106	85	71	57	22	8	1
2010	99	84	70	56	13	3	1
2011	99	84	70	56	10	2	0
2012	99	85	70	55	16	2	0
2013	99	85	71	57	12	6	0
2014	99	86	72	58	15	5	0
2015	106	87	74	60	18	7	1
2016	99	88	73	57	17	8	0
2017	99	90	75	60	30	17	8