October 2023 Monthly Global Climate Report

October 2023 Global Climate Report | National Centers for Environmental Information (NCEI)

Temperature

Coinciding with the release of the January 2023 Global Climate Report, the NOAA Global Surface Temperature (NOAAGlobalTemp) dataset version 5.1.0 replaced version 5.0.0. This new version includes complete global coverage and an extension of the data record back in time an additional 30 years to January 1850. While anomalies and ranks might differ slightly from what was reported previously, the main conclusions regarding global climate change are very similar to the previous version. Please see our Commonly Asked Questions Document and web story for additional information.

NOAA's National Centers for Environmental Information calculates the global temperature anomaly every month based on preliminary data generated from authoritative datasets of temperature observations from around the globe. The major dataset, NOAAGlobalTemp version 5.1.0, updated in 2023, uses comprehensive data collections of increased global area coverage over both land and ocean surfaces. NOAAGlobalTempv5.1.0 is a reconstructed dataset, meaning that the entire period of record is recalculated each month with new data. Based on those new calculations, the new historical data can bring about updates to previously reported values. These factors, together, mean that calculations from the past may be superseded by the most recent data and can affect the numbers reported in the monthly climate reports. The most current reconstruction analysis is always considered the most representative and precise of the climate system, and it is publicly available through Climate at a Glance.

October 2023

The October global surface temperature was 1.34°C (2.41°F) above the 20th-century average of 14.0°C (57.1°F), making it the warmest October on record. This was 0.24°C (0.43°F) above the previous record from October 2015. October 2023 marked the 47th-consecutive October and the 536th-consecutive month with temperatures at least nominally above the 20th-century average. The past 10 Octobers (2014–2023) have been the warmest Octobers on record.

October saw a record-high monthly global ocean surface temperature for the seventh consecutive month. El Niño conditions that emerged in June continued into October, and according to NOAA's Climate Prediction Center there is an 80% chance that El Niño will continue through the Northern Hemisphere spring (March–May 2024).

Temperatures were above average throughout most of North America, South America, western, southern, and eastern Europe, Africa, Asia, Oceania and the Arctic. Parts of Central and South America, Africa, Europe, northeastern North America and central Asia experienced record-warm temperatures this month. Sea surface temperatures were above average across much of the northern, western and eastern Pacific as well as the northern Atlantic and the Indian Oceans. Record-warm temperatures covered nearly 11% of the world's surface this October, which was the highest percentage for October since the start of records in 1951.

Temperatures were near to cooler than average across parts of Antarctica, southern South America, north-central North America, the Nordic countries, Greenland and northern Oceania. Sea surface temperatures were near to below average over parts of the southeastern Pacific Ocean, the eastern Indian Ocean and the southern Atlantic Ocean. Less than 1% of the world's surface had a record-cold October.

The Northern Hemisphere had its warmest October on record at 1.92°C (3.46°F) above average. Both land and ocean temperatures were at record-highs for the Northern Hemisphere this October. Meanwhile, the Southern Hemisphere had its third-warmest October on record at 0.77°C (1.39°F) above average. Only the Octobers of 2015 and 2018 had a higher average temperature in the Southern Hemisphere. However, the average ocean-only temperature for October in the Southern Hemisphere ranked warmest on record this October, while the land-only temperature ranked 15th warmest on record for the month.

A smoothed map of blended land and sea surface temperature anomalies is also available.

South America and Asia each had their warmest October on record.

Bolivia had its warmest October on record.
- October in Peru also ranked warmest on record.
Hong Kong had its fourth-warmest October on record.
- At 1.5°C above normal, October 2023 in Turkey ranked seventh warmest on record.
- October in Pakistan was 1.00°C above the long-term average.

October 2023 ranked second warmest on record for North America, Africa, and Europe.

Italy recorded its warmest October on record.
Spain had its second-warmest October on record.
- October in France ranked second warmest on record.
- October in Austria ranked warmest on record.
Switzerland also recorded its second-warmest October since records began in 1864.
- October in The Netherlands ranked sixth warmest on record.
- Meanwhile, Norway, Sweden, Finland, and Estonia recorded cooler-than-average temperatures for October.
The contiguous U.S. had its 18th-warmest October in the 129-year record.

October in Oceania ranked 15th warmest on record.

New Zealand had an October temperature that was 0.4°C above its 1991–2020 average.
- October in Australia was 1.05°C above the 1961–1990 average.

| October | Anomaly | | Rank(out of 174 years) | |
| °C | °F | Year(s) | | |
| Global | | | | |

Ocean Land and Ocean Land Ocean Land and Ocean Land Ocean Land and Ocean

500 mb maps

In the atmosphere, 500-millibar height pressure anomalies correlate well with temperatures at the Earth's surface. The average position of the upper-level ridges of high pressure and troughs of low pressure—depicted by positive and negative 500-millibar height anomalies on the map—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

Year-to-date Temperature: January–October 2023

The January–October global surface temperature ranked highest in the 174-year record at 1.13°C (2.03°F) above the 1901–2000 average of 14.1°C (57.4°F). This surpassed the previous record from January–October 2016 by 0.08°C (0.14°F). According to NCEI's statistical analysis and data through October, there is a greater than 99% chance that 2023 will rank as the warmest year on record.

January–October in the Northern Hemisphere ranked warmest on record at 1.44°C (2.59°F) above average. The ocean-only temperature also ranked highest on record, while the average land-only temperature for this year-to-date period ranked second highest on record in the Northern Hemisphere. January–October in the Southern Hemisphere also ranked warmest on record at 0.81°C (1.46°F) above average. The ocean-only temperature ranked record-high while average land-only temperature ranked third highest on record for the Southern Hemisphere.

South America, Africa, and Europe had their warmest year-to-date periods, while it was Asia's second-warmest such period on record. North America had its fourth-warmest such period. January–October 2023 ranked 12th warmest on record for Oceania.

A smoothed map of blended land and sea surface temperature anomalies is also available.

January to October was characterized by warmer-than-average conditions across much of eastern, southern, and northern North America, South America, Europe, Africa, the Arctic, Oceania, and Asia. Sea surface temperatures were above-average throughout most of the northern, western, and subtropical eastern Pacific, Atlantic, and Indian Oceans. The Arctic region had its fifth-warmest January–October period on record.

Temperatures were near or below average across parts of western North America, Greenland, and Antarctica. Sea surface temperatures were near to below average across parts of the southeastern and central-east Pacific Ocean.

| January–October | Anomaly | Rank(out of 174 years) | Records | |
| | °C | °F | Year(s) | °C |
| Global | | | | |

Ocean Land and Ocean Land Ocean Land and Ocean Land Ocean Land and Ocean

Precipitation

The maps shown below represent land-only precipitation anomalies (left, using a base period of 1961–1990) and land-only percent of normal precipitation (right, using the period of record) based on the GHCN dataset of land surface stations.

October 2023

Above-average October precipitation was observed across parts of the north-central and northeastern U.S., western and northern Europe, western Russia, and equatorial western Africa. Meanwhile, drier-than-average conditions were present across parts of the western U.S., northern, eastern, and southern South America, northern Africa, southeastern Europe, eastern Asia, and Oceania.

Global Precipitation Climatology Project (GPCP)

The following analysis is based upon the Global Precipitation Climatology Project (GPCP) Interim Climate Data Record. It is provided courtesy of the GPCP Principal Investigator team at the University of Maryland.

October Highlights:

- The current El Niño and Indian Ocean Dipole (IOD) SST patterns are associated with the rainfall anomaly patterns from eastern Africa (floods), across the Indian and Pacific Oceans and into Central and South America (drought).
- The European drought was alleviated somewhat by above-average precipitation this month, but was accompanied by floods in the U.K. and Italy.
- The mean global precipitation for this October set the record for this month with a value 6% above its long-term mean.
- The intensity of the global Intertropical Convergence Zone (ITCZ) also set a record for October due to global warming and the current El Niño.

For this October, the South Asian Monsoon is ending as the general area of rain retreats southward (Fig. 1, top panel) and the Northern Hemisphere tropical cyclone season reaches its peak. The ITCZ is very evident over both ocean and land across the tropics, with only slight breaks, and the midlatitude storm tracks slant toward the east and poleward in both hemispheres. But, in addition, the ongoing El Niño seems to be spreading its influence farther afield and other large-scale effects are helping to produce the observed variations for this month (Fig. 1, middle and bottom panels). As usual, the result of tropical storm tracks can be identified in the anomaly fields, for example, toward the north from the Caribbean into the North Atlantic and also from the eastern Pacific into Mexico.

The tropical sea surface temperature (SST) field is dominated by the El Niño positive anomaly feature in the central and eastern Pacific, with a current Niño3.4 Index of +1.7C, an increase from last month. Negative SST anomalies surround much of Indonesia and New Guinea, forming a gradient couplet with the central Pacific. In addition, in the Indian Ocean, a positive (+1.8) Indian Ocean Dipole (IOD) has formed in the few months, defined as the SST gradient from the West Indian Ocean minus the East Indian Ocean. This positive IOD, with its positive SST anomalies off Africa, is often associated with El Niños and enhances those effects in the African/Asian/Australian region. These resulting SST patterns and the associated large-scale circulations produce the positive rainfall anomalies over the tropical central Pacific (Fig. 1, middle and bottom panels), the negative anomalies over the Maritime Continent and west into the Indian Ocean and the positive anomalies over parts of the western Indian Ocean and coastal Africa. Both the Niño3.4 and IOD indices being positive also point to rainfall deficits over Australia, as is seen in the anomaly maps. Figure 2 shows the El Niño composite anomaly map for past October El Niños, along with a repeat of this October's anomaly map and the two fields are very similar over the region, indicating the impact of the El Niño and the Indian Ocean SST feature. The correlation between the two fields in Fig. 2 over the tropics is now +0.35, actually a slight drop from last month, but showing the effect of the El Niño on the current tropical pattern.

These large-scale drivers over the tropics have practical implications. The El Niño, especially with the positive IOD, produces above average rainfall in east Africa as seen in Fig. 2. And after a long drought, especially in the Horn of Africa, the last month in that region had very heavy rains and flooding in Somalia, Ethiopia, South Sudan and Kenya. Just to the north, Cyclone Tej developed over the Arabian Sea and came ashore at the Oman/Yemen border causing flooding with a report of 375 mm of rain over 24 hrs. Even in tropical West Africa, floods and landslides occurred in Cameroon and Ghana, again with a similar feature for this October as in the composite for El Niño.

Further to the east, most of India was dry (like the El Niño composite), but Indochina (flooding in southern Myanmar) and much of China was wet, different from the composite. Much of the Maritime Continent, the eastern India Ocean and Australia were dry, as expected under El Niño conditions. Across the tropical Pacific, the ITCZ is very intense with above average rainfall, while there is a marked dry zone just to its north, which covers the Hawaiian Islands and their continuing drought. Intense positive anomalies extend northward from the ITCZ along the western coast of Central America and Mexico, partly associated with Hurricane Norma hitting Baja California and Hurricane Otis intensifying rapidly to a Category 5 over warm waters just before hitting Acapulco with devastating results.

South America is almost completely covered by negative anomalies, especially evident over the Amazon, undergoing a very significant drought, as is parts of Argentina, which had wildfires. A significant exception to this dryness is the positive anomaly extending from southeast Brazil, which had flooding, with the wet feature continuing into the South Atlantic. The overall pattern across South America generally fits the El Niño composite. North America has dry conditions this month over the southwest and southeast, with wetter conditions in between and across the Canada/U.S. border regions.

A band of positive precipitation anomalies across the North Atlantic extends into western Europe and continues across northern Asia. This feature, perhaps fed by or associated with tropical cyclones transitioning into mid-latitude storms, somewhat alleviated the ongoing drought in Europe with some flooding in the U.K. and even further to the southeast in northern Italy (Milan and Tuscany).

The 2.83 mm/d global mean value for this October (see Fig. 3) is a record high for this month of the year, 6% above the October global long-term mean and indicates the impact of the El Niño on the short-term and global warming on the long term. This peak came with contribution from both the land and ocean components. The intensity of the global ITCZ as measured by the average of the peak rainfall along the ITCZ at each longitude is also a record for this month of the year, indicating the contribution of this tropical feature to the long-term positive trend in high intensity rain areas.

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Citing This Report NOAA National Centers for Environmental Information, Monthly Global Climate Report for October 2023, published online November 2023, retrieved on November 15, 2023 from

https://www.ncei.noaa.gov/ access/ monitoring/ monthly-report/ global/ 202310.