For the first two weeks of September, the average maximum temperature in downtown San Francisco was 77.8 degrees Fahrenheit, making it the fifth-hottest start to the month since 1921.
Data from the oldest downtown meteorological station recorded the highest temperatures five years ago, when the average maximum temp hit 82.7 degrees between Sept. 1 and Sept. 11. The city’s hottest day ever was Sept. 1, 2017, when the maximum temperature reached 106 degrees.
The three other hot starts to September occurred in 1983, 1984, and 2004.
What does this mean in terms of climate change?
2022 has the fifth hottest start of September since 1921.
Meteorologist said we’re experiencing more fluctuating and warmer temperature since 1980s.
82.7
82
79.5
78.7
80
77.8
2022 average
5-year
average
highest
temperature
75
70
65
every year
average
highest
temperature
60
2020
1920
1945
1970
1995
Note: the time period shown above is between Sept. 1 to Sept. 11
2022 has the fifth hottest start of September since 1921.
Meteorologist said we’re experiencing more fluctuating and warmer temperature since 1980s.
5-year
average
highest
temperature
every year
average
highest
temperature
2022 average
77.8°F
1920
1945
1970
78.7
1983
1984
82
1995
79.5
2004
82.7
2017
2020
Note: the time period shown above is between Sept. 1 to Sept. 11
“The patterns for the more recent years, since the mid-1980s, seem to be warmer and, especially, more fluctuating,” said Charles Fisk, a member of the American Meteorological Society.
Compared to the years before 1980, the average temperature has increased by 2 degrees Fahrenheit. Meteorologists said this is consistent with how they would expect the climate to behave in the 21st century.
John P. Monteverdi, professor emeritus of meteorology at San Francisco State University, said the heat can likely be attributed to global warming, but scientists prefer to wait for all the data to see if there are any extenuating circumstances.
As long as the extreme heat continues, power outages will follow. Exactly that happened last week.
On Tuesday, Sept. 6, the hottest day of the latest heat spell at 98 degrees Fahrenheit, Pacific Gas and Electric provided a record-breaking 22,684 MW of power to its customers, 50 percent more than it would normally provide. The outage that day affected more than 210,000 people.
At around 3 p.m. last Thursday, the soaring temperatures also brought on a power outage in nearly a straight line from Dogpatch through to Noe Valley. Approximately 5,800 Pacific Gas & Electric customers lost power.
More than 95 percent of the utility’s customers got their power back in an hour, as PG&E dispatched crews to Shotwell Street and 20th Street for repairs while the distribution control center connected customers to other power sources. The remaining customers, who were served directly by the damaged equipment, had their power restored at 6:54 p.m.
Stress on the equipment, said Mayra Tostado, a PG&E spokesperson, explained the outage.
Two hottest days last week were when most outage happened, according to PG&E.
PG&E provided record-breaking 22,684 MW of power to customers last Tuesday, Sept. 6.
.
On Tuesday, the outages
affected 217,505 customers.
98°F
95
On Thursday, the outages
affected 11,085 customers,
including 5,800 in Mission.
90
87°F
85
80
75
70
max temp
65
64°F
62°F
60
min temp
55
09/01
09/02
09/03
09/04
09/05
09/06
09/07
09/08
09/09
09/10
09/11
Two hottest days last week were when most outage happened, according to PG&E.
PG&E provided record-breaking 22,684 MW of power to customers last Tuesday, Sept. 6.
217,505 customers
affected by outage
11,085 customers
affected, including
5,800 in Mission
98°F
95
87°F
max temp
64°F
62°F
55
min temp
09/01
09/06
09/08
09/11
“What was extreme in the 20th-century climate is less extreme now, in the new climate mode,” said Monteverdi.
“In other words, people would say, ‘Oh, that was a really hot day.’ But it’s going to be more typical.”
Wider swings from the average are also expected in the Bay Area, not only in temperature, but also in rainfall. This means there will be more droughts and cold snaps as well, said Monteverdi. However, although climate change is certainly a driver of unusual weather events, it is difficult to attribute every event directly to global warming until more data is collected, he said.
The Bay Area has always experienced a cool summer and its warmer weather in September, and that is still the case. But the difference is that the autumn heat is now liable to be more extreme. The data shows that the highest temperature every month in recent years is higher, compared to years before the 1980s.
Bay Area has always experienced a cool summer and its warmer weather in September.
But data shows the higest temperature every month in recent years is slightly higher than 40 years ago.
105
100
95
90
post-1980 highest
temp per month
85
80
75
70
65
60
pro-1980 highest
temp per month
55
Jan
Feb
Mar
Apr
May
Jun
Jul
Sep
Oct
Nov
Dec
Aug
Bay Area has always
experienced a cool summer and its warmer weather in September
But data shows the higest temperature every month in recent years is slightly higher than 40 years ago
pro-1980 highest
temp per month
post-1980 highest
temp per month
cooler
hotter
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Note: Data analysis process can be found here.
Indian summers follow a frost. Perhaps Mission Local (or the loyal readers) can coin an appropriate term for what used to be two warm weeks in October but now are randomly occurring episodes of heat. I have experienced warm fog on the golden gate bridge as well, rather than the usual cold stuff. We need new names for the Global Weirding we are experiencing locally.
Hi Janos, thanks for clarifying that. I consulted two meteorologists too and they told me the term doesn’t really apply to the west coast. So I’ve changed it in the article 🙂