Extreme Temperature Diary- Thursday September 9th, 2021/ Main Topic: The U.S. Just Saw Its Hottest Summer On Record…Early September Record Scoreboard And Climatological Review

The main purpose of this ongoing blog will be to track planetary extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I‚Äôll refer to extreme or record temperatures as ETs (not extraterrestrials).ūüėČ

Main Topic: The U.S. Just Saw Its Hottest Summer On Record…Early September Record Scoreboard And Climatological Review

Dear Diary. We have yet another alarming climate crisis alarm bell ringing loudly today. Most climatologists aren’t surprised that the National Center For Environmental Information reported that the United States just had its hottest summer on record. That big early summer heatwave in the Pacific Northwest evidently put the U.S. over the statistical top:

It‚Äôs time once again for our monthly climatological review. Here on this site we present monthly summaries near the 8th of each month, and each is available if you want to go back through my Extreme Temperature Diary archive under my “Record Scoreboard Climatological Reviews” category (located on the upper left hand corner of my home page):


I’m repeating my mantra from prior months:

August 2021 got ranked by the National Center for Environmental Information as 14th warmest, temperature wise, for the lower 48 states, or 114th coldest since records began being kept in 1895:


After a relatively cool July, New England had a hot August. Vermont and New Hampshire saw their hottest August on record. Only a few states saw near average temperatures.

Here are my two U.S. Daily Record Scoreboards updated through 9/09/2021 (data compiled from the following NCEI site):


DHMX= Daily High Max Reports. DLMN= Daily Low Min Reports. DHMN= Daily High Min Reports. DLMX=Daily Low Max Reports.

For these data sets all monthly ratios of  > 10 to 1 DHMX to DLMN or > 10 to 1 DLMN to DHMX are in bold type. The rankings are for the lower 48 states with the warmest ranking since 1895 of average temperatures being 127 and 1 being the coldest as of 2021. Blue colors represent cold months and red warm. Those months and years with counts close to a 1 to 1 ratio of highs to lows are colored black. Boldly colored months, such as June 2021, have ratios of more than 10 to 1 daily record highs to lows or lows to highs, and are either historically hot or cold, most of which have made news.

August 2021 had approximately a 2.4-1 ratio of record DHMX to DLMN individual record counts, so the color I used for this month was red on the top chart.

August 2021 had approximately a 2.6-1 ratio of record DHMN to DLMX individual record counts, so the color I used for this month was red on the bottom chart.

Due to climate change we are seeing less blue colors on these Record Scoreboards with time, and August 2021 certainly fit this trend. 

As stated, the ranking for August 2021 was 114, which was colored red. I color rankings +10 or -10 from the average ranking of 63 black, indicating that these are near average temperature wise. Record statistics matched up well with the ranking of 114 for August 2021.

As shown on both charts, we can see that September 2021 has gotten off to a neutral start with relatively few reports of records, but warmer than average conditions should continue for much of the month for most of the lower 48 states looking at meteorological models.

Also as mentioned, Summer 2021 was the hottest on record for the lower 48 states:

It’s amazing but not too surprising that a winter and spring drought across the West led to extreme warmth in summer. Conditions could have been much worse if the winter and spring drought were in the nation’s heartland. This possible pattern may have produced record warmth for the summer season as a whole east of the Rockies, substantially hurting agriculture. The Southeast had a typical summer. I know that in my hometown of Atlanta the old thermometer never rose above 95¬įF, and rainfall was plentiful. Usually we will have several days between 95¬į and 100¬įF, but not so this year.

Brief summary for August 2021: Most reports of record warmth came from a heatwave that occurred in the middle of the month that I dubbed Epsilon, occurring in the Pacific Northwest and from the southern Midwest into the Northeast. Most record chill was sporadically reported across most sections of the country.

Here is much more detailed August 2021 U.S. climatology as complied by NOAA:


Home News

Assessing the U.S. Climate in August 2021

Virtual tie with 1936 for warmest summer on record for contiguous U.S.; severe weather, flash flooding, record wildfires and tropical cyclones

During¬†meteorological summer¬†(June-August), the average temperature for the Lower 48 was 74.0¬įF, 2.6¬įF above average, nominally eclipsing the extreme heat of the Dust Bowl in 1936 by nearly 0.01¬įF and essentially tying 1936 for the warmest summer on record. A record¬†18.4 percent¬†of the contiguous U.S. experienced record-warm temperatures for this season. For August, the contiguous U.S. average temperature was also 74.0¬įF, 1.9¬įF above the 20th-century average and ranked as the 14th-warmest August on record. For the year to date, the contiguous U.S. temperature was 55.6¬įF, 1.8¬įF above the 20th-century average, ranking 13th warmest in the January-August record.

The summer precipitation total across the Lower 48 was 9.48 inches, 1.16 inches above average, ranking eighth wettest in the historical record. The August precipitation total for the contiguous U.S. was 3.09 inches, 0.47 inch above average, ranking 14th wettest in the 127-year period of record. The year-to-date precipitation total across the contiguous U.S. was 21.19 inches, 0.48 inch above the long-term average, ranking in the middle third of the January-August record. 

Devastating flash flooding and fatalities resulted from multiple events during August including Tropical Storm Fred in western North Carolina, convective flooding from a complex of storms across middle Tennessee, Hurricane Ida across Louisiana and portions of the Northeast in early September and from Tropical Storm Henri, also across parts of the Northeast. With 35 fatalities accounted for during August*, it was the deadliest month for flooding across the U.S. since Hurricane Harvey in 2017.

Wildfires continued to spread across the western U.S. during August as the Dixie Fire in north-central California became the second-largest fire in the state’s history. The Caldor Fire also in California grew rapidly during August, threatening South Lake Tahoe communities. Air quality remained a concern across the U.S. as ash and fine particulates from the many wildfires obscured the skies.

*The remnants of Hurricane Ida impacted the Northeast in early September, raising the 2021 fatality count outside of the August observation period.

This monthly summary from NOAA National Centers for Environmental Information is part of the suite of climate services NOAA provides to government, business, academia and the public to support informed decision-making.



  • August temperatures¬†were above average across the West Coast, Southwest and from the Plains to the East Coast.¬†Vermont¬†and¬†New Hampshire¬†both had their warmest August on record while¬†Maine¬†and¬†Massachusetts¬†ranked second warmest. Much of the above-average warmth can be attributed to warm¬†overnight temperatures. Temperatures were near to below average across much of the northern Rockies and the southern Plains.¬†
  • The¬†Alaska average August temperature¬†was 49.4¬įF, 0.1¬įF below the long-term mean, ranking in the middle third of the 97-year period of record for the state.¬†Temperatures¬†were above average across portions of the Southeast Interior, Panhandle and Aleutian regions. Temperatures were cooler than average across the North Slope, Northeast Interior, northern West Coast and parts of Bristol Bay. A persistent cold low-pressure system over the northern Chukchi-Beaufort Seas during August contributed to the cooler-than-average temperatures and the largest observed sea ice extent over the Chukchi Sea since 2006.


  • Precipitation¬†was above average across portions of the central and northern Rockies, the northern Plains, Great Lakes and from the Deep South to southern New England.¬†Mississippi¬†ranked fourth wettest while¬†Tennessee¬†had its fifth-wettest August on record. The Southwest monsoon continued to be active in August, eliminating much of the year-to-date precipitation deficit across the region. Tucson, Arizona, had its wettest August and second-wettest summer on record. Precipitation was below average across portions of the West, southern Rockies, central Plains, Midwest, northern Great Lakes and northern New England.
  • Statewide precipitation for Alaska was above average for August, but varied by region. Precipitation was below average across the Aleutians, Bristol Bay and Northwest Gulf regions while the interior regions, Northeast Gulf and Panhandle regions experienced above-average precipitation for the month.¬†
  • According to the August 31¬†U.S. Drought Monitor report, approximately 46.6 percent of the contiguous U.S. was in drought, slightly more than the coverage at the beginning of August. Drought conditions expanded or intensified across the Northern Tier, the Pacific Northwest and portions of California. Drought coverage and/or intensity lessened across parts of the Four Corners region, the Midwest, Hawaii and Puerto Rico and was eliminated in Alaska.¬†

An additional note on Hurricane Ida precipitation and temperature implications:¬†As is typical with very heavy rainfall events, localized bands of very heavy rain may not be completely captured by the gauge-based observing network, which is the basis for this analysis. This circumstance can lead to an underrepresentation of actual rainfall totals. The issue can be compounded by disruptions to the observers’ ability to report values during or following a severe event and, in this case, several of our reporting stations posted missing data for both temperature and precipitation during this event. Additionally, quality assurance routines may flag large valid precipitation values as erroneous, resulting in underestimated values. NCEI is working to ensure all reports are indeed validated. As a result, a more complete accounting of the temperature statistics and precipitation across Louisiana during August will be available with the September report.

Summer (JuneAugust)


  • Summer temperatures¬†were above average to record warmest from the West Coast to the Great Lakes and into the Northeast as well as across portions of the Mid-Atlantic and Gulf Coast.¬†California,¬†Nevada,¬†Utah,¬†Oregon¬†and¬†Idaho¬†each reported their warmest June-August on record. Sixteen additional states had a top-five warmest summer on record. No state ranked below average for the summer season. Temperatures were below average across portions of the southern Plains and Southeast. Warm¬†overnight temperatures¬†heavily influenced the warm summer temperatures, especially across portions of the Southeast, where¬†daytime temperatures¬†were below average for the season.
  • The¬†Alaska¬†statewide average temperature for the summer was 51.4¬įF, 1.0¬įF above average and ranked in the warmest one-third of the 97-year record. Temperatures were warmer than average across much of the eastern half of the state as well as across the Aleutians and near average for much of the rest of the state.


  • Precipitation¬†was above average across portions of the Great Basin and Southwest,¬† from the southern Plains to the Great Lakes and across much of the eastern U.S.¬†Mississippi¬†had its wettest summer on record with¬†Alabama,¬†Michigan,¬†New York¬†and¬†Massachusetts¬†ranking among their five wettest summers on record. Precipitation was below average from the Northwest to the western Great Lakes and into the central Plains.¬†Minnesota¬†had its seventh-driest summer on record.¬†
  • Precipitation in Alaska was above average across much of the northern half of the state as well as across portions of the Northeast Gulf and Panhandle regions. Precipitation was below average in the southwestern portion of the state. Kotzebue had its wettest summer on record, reporting 9.21 inches and besting the previous record, set in 1963, by nearly an inch. The wildfire season was well-below average with only 254,000 acres consumed ‚ÄĒ less than half of the median value.

Year-to-date (JanuaryAugust)


  • Year-to-date temperatures¬†were above average from the West Coast to the Great Lakes and into the Northeast as well as across parts of the Mid-Atlantic and Southeast.¬†California¬†and¬†Maine¬†each reported their third-warmest January-August on record. Sixteen additional states had a top-ten warmest year-to-date period. Temperatures were below average across much of the southern Plains and lower Mississippi Valley.
  • Year-to-date temperatures across¬†Alaska¬†were near average with above-average temperatures observed across the southwestern portion of the state. Much of the rest of the state experienced near average temperatures for this period.


  • January-August precipitation¬†was above average from the Deep South to the Midwest, across the Southeast and portions of the Northeast.¬†Mississippi¬†had its third-wettest such year-to-date period on record. Precipitation was below average from the West Coast to the western Great Lakes and across portions of northern New England.¬†Montana¬†ranked fifth driest while three additional states ranked among the driest 10 January-August periods on record.¬†
  • For Alaska, January-August precipitation was above average across the West Coast, North Slope and from the Central Interior to the Panhandle. Precipitation was below average in parts of the Cook Inlet region.

For more detailed climate information, check out our comprehensive August 2021 U.S. Climate report scheduled for release on September 14, 2021.

Here are some “ET’s” from Thursday:

Here is some more August 2021 climatology:

Here is more climate and weather news from Thursday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)


Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton ‚ÄúThe Climate Guy‚ÄĚ

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