Earth Tied Its Record Warmest September in 2019, NOAA Finds

Jonathan Erdman
Published: October 16, 2019

September 2019 tied for Earth's warmest September in 140 years of temperature records, according to a government report, continuing a warming trend that keeps 2019 on pace for one of the warmest years dating to 1880.

NOAA's September Global State of the Climate Report released Wednesday found global land and ocean temperatures were 0.95 degrees Celsius (1.7 degrees Fahrenheit) above the 20th-century average.

That may not sound impressive, but in the realm of global temperatures, this warm anomaly tied 2015 as the planet's warmest September, in NOAA records dating to 1880.

Ultimately, what's most important is not whether a given month is a fraction of a degree warmer or colder. Rather, it's the overall trend, which continues its upward climb since the late 1970s.

September 2019 marked the 417th consecutive month and 43rd straight September that global temperatures have been above average in NOAA's database.

The eastern U.S. and parts of Brazil, Mongolia and China were among the areas much warmer than average in September. NOAA's report said it was the hottest September on record in North America and the Gulf of Mexico, in records dating to 1910.

Parts of western Russia, the western U.S. and Indonesia were among the few cooler than average land areas in September, according to NOAA's analysis.

This graph shows monthly global temperature anomalies in degrees Celsius relative to 1980-2015, for each year from 1880 through September 2019, with the warmer, more recent years reflected in the top plots and cooler years of the past in the bottom plots, according to the legend in the upper left corner. September 2019 is labeled.

Other expert analyses came to a similar conclusion.

NASA's Goddard Institute for Space Studies found September 2019 global average temperatures across all land and ocean surfaces were only 0.01 degrees Celsius behind 2016 as the warmest September in their records also dating to 1880.

It was the 13th straight month in the top five warmest respective month in NASA's database, a streak that began in September 2018.

Since 2015, 49 of the last 57 months have at least tied a top five warmest respective month, according to NASA-GISS. From October 2015 through September 2016, 10 months set records.

Rankings of monthly global temperatures, according to the NASA-GISS database since 2015. Circled '1s' highlight months setting a record high temperature for the month. Ties among months during those four-plus years are indicated by the same ranking given to each month.
(Data: NASA-GISS; Table: Infogram)

Another analysis, from the Japan Meteorological Agency, also found September 2019 was the globe's second-warmest June, behind only 2015. The JMA analysis found the planet's five warmest Septembers have all come in the last six years.

Earlier in the month, Europe's Copernicus Climate Change Service (C3S) also found September to have topped the previous record-warmest September in 2016 by 0.02 degrees Celsius.

Will 2019 Become Earth's Warmest Year on Record?

NOAA's report said 2019 was the second-warmest first nine months of any year, trailing only 2016.

Parts of central and southern Africa, the Indian Ocean, Australia, New Zealand, Asia, Europe, Alaska, Central America and northern South America had record warmth over the first nine months of 2019, according to NOAA.

January-September 2019 global temperature percentiles. Areas in darkest red indicate it was a record warm January-September period in 2019.

Given each month this year has been at least the fourth-warmest respective month, what are the odds 2019 will end up as the hottest year on record?

In his monthly update, climate scientist James Hansen said 2019 is unlikely to surpass 2016.

A record-tying strong El Niño lasted through roughly the first half of 2016, giving a boost to global temperatures. A much weaker El Niño was in place in the first half of 2019, and the lack of a stronger push from that event may be the dominant factor that keeps 2019 from becoming Earth's warmest year.

Because much of the increasing heat trapped in Earth's oceans is tucked away at depth, surface air temperatures are generally warming more quickly over land than over water.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.