Global Temperatures
The year 2023 was the warmest year since global records began in 1850 at 1.18°C (2.12°F) above the 20th century average of 13.9°C (57.0°F). This value is 0.15°C (0.27°F) more than the previous record set in 2016. The 10 warmest years in the 174-year record have all occurred during the last decade (2014–2023). Of note, the year 2005, which was the first year to set a new global temperature record in the 21st century, is now the 12th-warmest year on record. The year 2010, which had surpassed 2005 at the time, now ranks as the 11th-warmest year on record.

During 2023, each monthly global surface temperature anomaly value ranked among the seven warmest with June through December each ranking as the warmest such month on record. The July global temperature value was likely the warmest of all months on record and the July, August, and September temperature anomalies each exceeded 1.0°C (1.8°F) above the long-term average for the first time on record. The September anomaly value of 1.44°C (2.59°F) was the largest positive monthly global temperature anomaly for any month on record.

Global ocean temperatures in 2023 were also noteworthly with nine-consecutive months (April–December) of record warm temperatures. The September ocean temperature anomaly value (+1.04°C/+1.87°F) was warmest of any month on record.

The Northern Hemisphere summer season (June–August) was warmest on record and the Northern Hemisphere autumn (September–November) was not only the warmest such period on record, it exceeded the previous record from 2015 by 0.39°C (0.70°F) and was the largest positive seasonal anomaly for any season on record in the Northern Hemisphere. The 2023 Northern Hemisphere surface temperature was also warmest on record at +1.54°C (+2.77°F). Meanwhile, the Southern Hemisphere had its warmest year on record, with a temperature that was 0.82°C (1.48°F) above the 20th century average.