In 2023, temperatures were warmer than average over the vast majority of the Earth’s surface. Areas of notable warmth include the Arctic, northern North America, central Asia, the North Atlantic and the eastern tropical Pacific. Temperatures were cooler than average over relatively smaller areas, such as eastern and western Antarctica, the Southern Ocean near western Antarctica and southern Greenland. 

In the upper ocean heat content, the amount of heat stored in the top 2000 meters of the ocean was record-high in 2023. Ocean heat content is a key climate indicator because the oceans store 90% of the excess heat in the Earth system. The indicator has been tracked globally since 1958, and there has been a steady upward trend since about 1970. The five highest values have all occurred in the last five years.

The year of 2023 had a slightly below average cover of snow which covered over an average 9.4 million square miles. Monthly extent ranged from 17.8 million square miles in January to just under 1.0 million square miles in August, both of which were below average. Snow cover extent records began in 1967.

78 named storms occurred across the globe in 2023, which was below the 1991–2020 average of 87.5. 45 of those reached tropical cyclone strength (≥74 mph), and 30 reached major tropical cyclone strength (≥111 mph). These also included seven storms that reached Category 5 (≥157 mph) on the Saffir-Simpson hurricane wind scale. The global accumulated cyclone energy (ACE) was about 8% above the 1991–2020 average. In 2023, temperatures were warmer than average over the vast majority of the Earth’s surface.