Assessing the Global Climate in September 2023

September Highlights:

• Last month, the January–September 2023 period surpassed January–September 2016 as the warmest such year-to-date period on record.
• Record-warm temperatures covered 20% of the world’s surface this September, which was the highest percentage of any month since the start of records in 1951.
• After two months of below-average temperatures, Antarctica had its warmest September on record while sea ice continued to track at record low levels.
• With 17 named storms across the globe this September, the global accumulated cyclone energy was about 70% of the 1991-2020 average.

Globally, September 2023 was the warmest September in the 174-year NOAA record. The year-to-date (January–September) global surface temperature ranked as the warmest such period on record. According to NCEI’s Global Annual Temperature Outlook and data through September, there is a greater than 99% probability that 2023 will rank as the warmest year on record.

“September 2023 was the fourth month in a row of record-warm global temperatures,” said NOAA Chief Scientist Dr. Sarah Kapnick. “Not only was it the warmest September on record, it was far and away the most atypically warm month of any in NOAA’s 174 years of climate keeping. To put it another way, September 2023 was warmer than the average July from 2001-2010.”

This monthly summary, developed by scientists at 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.

Monthly Global Temperature

The September global surface temperature was 2.59°F (1.44°C) above the 20th-century average of 59.0°F (15.0°C) and ranks as the warmest September in NOAA’s 174-year record. This was 0.83°F (0.46°C) above the previous record from September 2020 and marks the highest monthly global temperature anomaly of any month on record. The September 2023 global temperature anomaly surpassed the previous record-high monthly anomaly from March 2016 by 0.16°F (0.09°C). September 2023 marked the 49th-consecutive September and the 535th-consecutive month with temperatures above the 20th-century average. 

North America, South America, Europe and Africa each had their warmest September on record. Asia had its second-warmest September, while September in Oceania ranked third warmest. For the sixth consecutive month, September saw a record-high monthly global ocean surface temperature. September 2023 tied August 2023 for the highest monthly sea surface temperature anomaly (+1.85°F or +1.03°C) of any month in NOAA’s 174-year record. Antarctica had its warmest September, while September in the Arctic ranked second warmest on record.

Temperatures were above average throughout most of North America, South America, Europe, Africa, Asia, Oceania and Antarctica. Parts of Europe, southern and north-central North America, northern and central South America, western and eastern Africa, southwestern and central eastern Asia, southwestern Oceania and Antarctica experienced record-warm temperatures this month. Sea surface temperatures were above average across much of the northern, western and southwestern Pacific as well as the Atlantic and the Indian Ocean. Record-warm temperatures covered 20% of the world’s surface this September, which was the highest percentage of any month since the start of records in 1951.

Temperatures were near to cooler than average across parts of southern South America and central Russia. Sea surface temperatures were near to below average over parts of the southeastern Pacific Ocean. Less than 1% of the world’s surface had a record-cold September.

Sea Ice Extent

September 2023 set a record for the lowest global September sea ice extent on record. This primarily resulted from record-low sea ice extent in the Antarctic, which saw its fifth consecutive month with the lowest sea ice extent on record. Globally, September 2023 sea ice extent was 590,000 square miles less than the previous record low from September 2016.

The Arctic sea ice extent for September 2023 ranked as the fifth smallest in the satellite record at 1.69 million square miles, or 470,000 square miles below the 1991–2020 average. On September 19, the National Snow and Ice Data Center (NSIDC) announced that Arctic sea ice likely reached its annual minimum extent of 1.63 million square miles. This year’s Arctic minimum ranks sixth lowest in the 45-year record. 

Sea ice extent in the Antarctic ranked lowest on record at 6.49 million square miles, which was 700,000 square miles below the 1991–2020 average. NSIDC announced a record-low annual Antarctic sea ice maximum extent at 6.55 million square miles on September 10. This set a record low maximum in the satellite record that dates back to 1979, beating out the previous record low set in 1986 by 398,000 square miles.

Global Precipitation

The ongoing El Niño dominated rainfall anomaly patterns from the eastern Indian Ocean, across the tropical Pacific and into Central America and northern South America. The South Asian Monsoon was wetter than average over land and drier to the south over the ocean. Drought in Europe continued, but floods in Greece and Libya were tied to a warm Mediterranean and a tropical-like circulation pattern. The rainfall intensity of the global Intertropical Convergence Zone (ITCZ) set a record for September due to global warming combined with current El Niño conditions.

Global Tropical Cyclones

Seventeen named storms occurred across the globe in September. Seven of those reached tropical cyclone strength (≥74 mph), and four reached major tropical cyclone strength (≥111 mph). The global accumulated cyclone energy was about 70% of the 1991-2020 average for September. Ten named storms were active in the Atlantic during September, which tied 2010 and 2020 for the most on record.

For a more complete summary of climate conditions and events, see our September 2023 Global Climate Report or explore our Climate at a Glance Global Time Series.