Extreme Temperature Diary- Tuesday October 10th, 2023/Main Topic: U.S. 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’ll refer to extreme or record temperatures as ETs (not extraterrestrials). 😉

Main Topic: U.S. September Record Scoreboard and Climatological Review

Dear Diary. It’s time once again for our monthly climatological review. Here on this site, we usually present monthly summaries near the 10th of each month, and each is available by clicking the link below:


I’m repeating this mantra every month:

September 2023 using 1901-2000 mean data got ranked by the National Center for Environmental Information for the lower 48 states as 7th warmest, or 123rd coolest since records began being kept in 1895.


Overall, during September we saw another heat dome develop from the southern tier of states that produced what I dubbed Heatwave Dana. The Southeast and far West were the coolest corners of the nation, but no one state saw below average temperatures. Statistically as a whole, the U.S. had a well above average month. As depicted below, two states had their hottest Septembers on record:

Here are my two U.S. Daily Record Scoreboards updated through 10/10/2023 (data compiled from the following NCEI site):


I’m also keeping tabs on record report totals to verify a scientific study I helped to complete in the decade of the 2000s. We’ll eventually see how skewed ratios of record warm to cold reports get by the year 2100, which the study mentions as 50-1 for DHMX vs. DLMN:

Relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S. – Meehl – 2009 – Geophysical Research Letters – Wiley Online Library

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

Totals are record reports for the entire United States including all territories minus those from Alaska. I’ve subtracted those from Alaska to get a better representation of what has occurred across the lower 48 states in association with lower 48 state rankings.

Bold red, blue, or purple colored months, such as January 2020 and June 2021, that have ratios of >10 to 1 daily warm low records or <1 to 10 daily warm to low records are either historically hot or cold, most of which have made news. NCEI rankings are for the lower 48 states with the warmest ranking since 1895 of average temperatures being 128 (for ties) or 129 and 1 being the coldest as of 2023. 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. All-time record hottest or coldest months and years are boldly colored in purple. NCDC rankings have been color coded (under tabs in each file) such that values of 54 to 74 are black representing neutral months or years (+ or – 10 from the average ranking of 64).

Record numbers statistically matched up well during September of 2023 with that month being the 7th warmest September on record, which was well above average. Just about every time we see a month with a greater than 10 to 1 ratio of DHMX to DLMN records we have a top ten average month.

September 2023 had approximately a 11 to 1 ratio of record DHMX to DLMN individual record counts, so the color I used for this month was bold red on the top chart.

September 2023 had approximately a 24 to 7 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 fewer blue colors on these Record Scoreboards with time.

As stated, the average temperature lower 48 state ranking for September 2023 was 123, which was colored red since it was above average.

I color rankings of +10 to -10 from the average ranking for the lower 48 states of 64.5 black, indicating that these are near average temperature wise. The top warmest ranking for 2023 would be 129 since rankings began in 1895.

We are seeing that October 2023 has gotten off to a very warm start, but anomalous heat ended after the 6th. A much cooler pattern has ensued across the eastern two thirds of the United States, which will continue through the remainder of the month, so I doubt that October 2023 will be a third consecutive top ten ranked month.

After a relatively cool start to the year, 2023 now has record ratios near those of the first three years of this decade:

Here is much more detailed climatology for September 2023 as complied by NOAA:

Assessing the U.S. Climate in September 2023 | News | National Centers for Environmental Information (NCEI) (noaa.gov)

Assessing the U.S. Climate in September 2023

Coastal storms brought heavy rains and flooding to the East Coast; 111 counties had their warmest September on record

Key Points:

  • Hurricane Lee, Tropical Storm Ophelia and a slow-moving coastal low brought record-breaking precipitation and widespread flooding across parts of the East Coast.
  • Near-record to record-warm temperatures were observed across much of the southern Plains and Upper Midwest this month.
  • Year-to-date averages across the eastern U.S. have been warmer than average throughout 2023 with 30 states experiencing a top-10 warmest January–September.
  • A total of 24 separate billion-dollar weather and climate disasters have been confirmed this year—the most events on record during a calendar year.
  • September 2023 was the seventh-warmest September on record for the nation, and precipitation ranked in the driest third of the historical record for the month.

Other Highlights:


The average temperature of the contiguous U.S. in September was 67.8°F, 2.9°F above average, ranking seventh warmest in the 129-year record. Generally, September temperatures were above average across much of the contiguous U.S., with below-normal temperatures in southern parts of the West Coast and in parts of the Southeast. New Mexico and Texas ranked warmest on record for September while Minnesota ranked second warmest on record. An additional 10 states ranked among their top-10 warmest September on record.

The Alaska statewide September temperature was 40.6°F, ranking near normal in the 99-year period of record for the state. Near-normal temperatures were observed across much of the state with above-normal temperatures observed in parts of North Slope, the Aleutians and Panhandle, while below-normal temperatures were observed in parts of the Interior and southwest Alaska. 

For the January–September period, the average contiguous U.S. temperature was 57.0°F, 1.9°F above average, ranking 10th warmest on record for this period. Temperatures were above average from parts of the Southwest to the East Coast and along parts of the Northern Tier, with near- to below-average temperatures from parts of the northern Plains to the West Coast. Texas, Louisiana, Mississippi and Florida each ranked warmest on record while Delaware and Maryland each ranked second warmest for the January–September period. An additional 24 states had a top-10 warmest year-to-date period. No state experienced a top-10 coldest event for this nine-month period. 

The Alaska January–September temperature was 31.9°F, 1.8°F above the long-term average, ranking in the warmest third of the historical record for the state. Much of the state was above normal for the nine-month period while temperatures were near average across much of western Alaska and in parts of the Interior.


September precipitation for the contiguous U.S. was 2.10 inches, 0.39 inch below average, ranking in the driest third of the historical record. Precipitation was below average across much of the Mississippi Valley, Great Lakes and Ohio and Tennessee valleys as well as in parts of the Southwest, southern Plains and Southeast. Precipitation was above average across much of the West and northern Plains and along parts of the East Coast. Connecticut had its third-wettest September on record, while two additional states ranked among their top-10 wettest for this period. On the dry side, Ohio ranked fifth driest on record for the month with two additional states ranking among their top-10 driest September on record.

Across the state of Alaska, the average monthly precipitation was 5.05 inches, ranking in the middle third of the historical record. Precipitation was near average across much of the state while wetter-than-average conditions were observed across parts of the North Slope, eastern Interior and Panhandle. Below-normal precipitation was observed in parts of Southwest Alaska, including parts of the Aleutians, during the month.

The January–September precipitation total for the contiguous U.S. was 23.32 inches, 0.12 inch above average, ranking in the middle third of the 129-year record. Precipitation was near to above average from California to the western Great Plains, in the Northeast and in parts of the Mid-Mississippi Valley, northern Great Lakes and Southeast. Massachusetts ranked second wettest, while Connecticut ranked third wettest on record for this year-to-date period. Six additional states ranked among their top-10 wettest for this period. Conversely, precipitation was below average along parts of the Northern Tier, from parts of the Southwest to the Gulf of Mexico and in parts of the upper and central Mississippi Valley and Mid-Atlantic during the January–September period. Iowa ranked 10th driest for this nine-month period.

The January–September precipitation ranked 14th wettest in the 99-year record for Alaska, with above-average precipitation observed across much of the state. Near- to below-normal precipitation was observed along parts of the Gulf of Alaska, while parts of the Aleutians experienced below-average precipitation during this period.

Billion-Dollar Disasters

One new billion-dollar weather and climate disaster was confirmed this month after a drought and heatwave event that affected portions of the Southern and Midwestern U.S. this year.

There have been 24 confirmed weather and climate disaster events this year, each with losses exceeding $1 billion. These disasters consisted of 18 severe storm events, two flooding events, one tropical cyclone, one winter storm, one wildfire and one drought and heatwave event. For this year-to-date period, the first nine months of 2023 rank highest for disaster count, ahead of those of 2017 and 2020 which both saw 17 disasters. The total cost of the 2023 events exceeds $67.1 billion, and they have resulted in 373 direct and indirect fatalities. 

The U.S. has sustained 372 separate weather and climate disasters since 1980 where overall damages/costs reached or exceeded $1 billion (including CPI adjustment to 2023). The total cost of these 372 events exceeds $2.630 trillion.

Other Notable Events

Persistent heat brought record-breaking temperatures to portions of the U.S. during September:

  • It was the warmest September on record for Texas by nearly 0.3°F, and New Mexico tied with 2015 and 2019 as the warmest September on record. 
  • A total of 111 counties had their warmest September on record while an additional 582 counties ranked in the top-10 warmest for the month. For the January–September period, 317 counties were record warm while an additional 1,450 counties ranked in the top-10 for this year-to-date period. There are 3,143 counties in the U.S.
  • Record-high temperatures have persisted across much of Puerto Rico and the U.S. Virgin Islands during the month of September. San Juan reported a monthly average temperature of 85.8°F, making it the hottest month on record. Also, on St. Croix, Rohlsen Airport had their warmest September on record.
  • Warm temperatures and lack of rainfall resulted in persistent drought across parts of the Midwest, leading to near-record low water levels along parts of the Mississippi River and creating saltwater intrusion concerns in southern Louisiana.

Several notable storms impacted portions of the U.S. in September:

  • Hurricane Lee brought catastrophic flash flooding and damage to portions of New England.
  • On September 23, Tropical Storm Ophelia made landfall in eastern North Carolina and moved north along the East Coast. Ophelia brought heavy rainfall and flooding from North Carolina to Massachusetts, resulting in significant damage and power outages.
  • On September 24-26, a bomb cyclone brought heavy precipitation to much of the Pacific Northwest. Seattle had three of their five wettest days so far this year—the precipitation total was more than double of what the city received over the entire summer season.
  • On September 29, a slow-moving storm brought heavy rainfall to New York City, grounding flights, flooding roads and subways and trapping residents in their homes. Parts of Brooklyn reported more than 7 inches of rainfall, while John F. Kennedy Airport received 8.65 inches—setting a new 24-hour precipitation record for the month which was previously set by Hurricane Donna in 1960.


According to the October 3 U.S. Drought Monitor report, about 40.1% of the contiguous U.S. was in drought, up about 5.8% from the end of August. Moderate to exceptional drought was widespread across much of the Great Plains, Lower Mississippi Valley and Southwest, with moderate to extreme drought along the Northern Tier and in parts of the Florida Peninsula and Hawaii. Moderate to severe drought was present in parts of the Mid-Atlantic and New York, as well as moderate drought in parts of the Ohio Valley, Southeast and Puerto Rico.

Drought conditions expanded or intensified across much of the Ohio and Tennessee valleys and Lower Mississippi Valley, and in parts of the Northwest, Southwest, eastern Plains, Hawaii and Puerto Rico this month. Drought contracted or was reduced in intensity across portions of the Northern Tier, western Plains, Upper Midwest and Mid-Atlantic.

Monthly Outlook

According to the September 30 One-Month Outlook from the Climate Prediction Center, much of the contiguous U.S. and much of Alaska favor above-normal monthly average temperatures in October, with the greatest odds in parts of north-central U.S. and northern Alaska. Below-normal temperatures are not forecasted for any parts of the contiguous U.S. or Alaska this month. Large portions of the West and Alaska are favored to see above-normal monthly total precipitation while below-normal precipitation is most likely to occur from the Mississippi Valley to the East Coast and in small parts of the Northwest. Drought improvement or removal is forecast in parts of the Plains, Florida Peninsula and Puerto Rico, while persistence is more likely across the Northern Tier, Southwest, Mississippi Valley, Ohio Valley, Mid-Atlantic and Hawaii. Drought development is likely in parts of the Northwest and Southeast.

According to the One-Month Outlook issued on October 1 from the National Interagency Fire Center, Hawaii and from the Lower Mississippi Valley to parts of the Mid-Atlantic have above-normal significant wildland fire potential during October, while parts of southern coast of California are expected to have below-normal potential for the month.

This monthly summary from NOAA’s 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. For more detailed climate information, check out our comprehensive September 2023 U.S. Climate Report scheduled for release on October 13, 2023. For additional information on the statistics provided here, visit the Climate at a Glance and National Maps webpages.

Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:

Here is some more brand-new September 2023 climatology:

Here is More Climate and Weather News from Tuesday:

(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.)

Today’s News on Sustainable, Traditional Polluting Energy from Fossil Fuel, and the Green Revolution:

More from the Weather Department:

More on the Environment:

More on Other Science and the Beauty of Earth and this Universe:

If you like these posts and my work on record temperature ratios, please contribute via my PayPal widget on this site. Thanks in advance for any support. 

Guy Walton… “The Climate Guy”

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