May 2023 Temperature Update

The following is a summary of global temperature conditions in Berkeley Earth’s analysis of May 2023.

  • Globally, May 2023 was slightly cooler than April and nominally for the 3rd warmest May since records began in 1850.
  • In the oceans, May 2023 set a new record for the warmest May since 1850.
  • On land, May 2023 was the 10th warmest May since 1850.
  • Warm conditions occurred in Canada, parts of South America and Africa, the Eastern Equatorial Pacific, the North Atlantic, and the Southern Indian Ocean.
  • Unusually cool conditions were present in Australia, India, parts of Antarctica.
  • The Pacific transitioned towards El Niño, which was officially declared to have begun in early June.
  • 2023 is now more slightly likely than not to become a new record warm year (54% chance).

Global Summary

Globally, May 2023 has been nominally the third warmest May since records began in 1850. This May was warmer than the previous two years, but still cooler than May in 2020 and 2016. May 2023 was distinctly warmer than any May prior to 2016.

The global mean temperature in May 2023 was 1.31 ± 0.10 °C (2.36 ± 0.18 °F) above the 1850 to 1900 average, which is frequently used as a benchmark for the preindustrial period. The global mean temperature anomaly in May 2023 exhibited a modest decrease relative to April 2023, falling ~0.1 °C (0.18 °F). Notably, temperature anomalies in May and April were significantly reduced from the extreme high in March.

Temperatures in May were close to the long-term trend line, and recent fluctuations remain consistent with natural variability within the ongoing pattern of global warming.

Spatial Variation

May 2023 continues the ongoing pattern of widespread warmth, though with a few exceptions. Particularly warm conditions were present in Canada, parts of South America and Africa, the Eastern Equatorial Pacific, the North Atlantic, and the Southern Indian Ocean.

Particularly cool conditions were present in Australia, India, parts of Antarctica.

We estimate that 5.4% of the Earth’s surface experienced their locally warmest May average, and 76% of the Earth’s surface was significantly warm when compared to their local average during the period 1951 to 1980. In addition, 0.03% of the Earth’s surface had their locally coldest May.

The Equatorial Pacific in May was transitioning towards El Niño conditions. Above average temperatures are present in much of the Pacific, with record warm temperatures developing in some areas near the coast of South America and beginning to extend westward into the central Equatorial Pacific. An El Niño condition was officially declared in early June.

Over land regions, 2023 was the 10th warmest May ever observed, and cooled modestly relative to April. The land average was 1.55 ± 0.19 °C (2.80 ± 0.34 °F) above the 1850 to 1900 average.

May 2023 was nominally the warmest May in the oceans, recorded as 1.01 ± 0.12 °C (1.81 ± 0.22 °F) above the 1850 to 1900 average. This beats the previous record for May, which was jointly held by 2020 and 2016, though the uncertainties on the new measurements still overlap with the previous record.

Despite being the warmest May on record in the oceans, the temperature anomaly is actually slightly cooler than April. As previously noted, the temperature anomaly of 1.07 °C in April 2023 was the largest temperature anomaly ever observed in instrumental measurements of the oceans.

El Niño Outlook

May 2023 exhibited a warming condition in the Pacific Ocean consistent with the emergence of a new El Niño. An El Niño Advisory — announcing the start of a new El Niño — was officially issued by NOAA’s Climate Prediction Center on June 8th. The current CPC/IRI analysis suggests that El Niño conditions will persist for the foreseeable future, at least until next year. Models currently disagree on the likely intensity of the current El Niño, with some models predicting a very strong event, while others are more mild or moderate. The intensifying warm pool in the Pacific will likely give us a clearer idea of what to expect during the next month or two.

El Niño is likely to moderately boost global average temperatures during the rest of 2023 and into 2024. Due to the lag between the development of El Niño and its full impact being felt on global temperatures, it is likely that the current El Niño will have a greater impact on 2024 global temperatures than it does on 2023.

Predictions of future sea surface temperatures in the core ENSO region from IRI/CPC.
Predictions of future El Niño/La Niña from IRI/CPC.

Year to Date

This year began with a January that was similar to January in 2021 and 2022. However, with the end of La Niña, temperatures diverged markedly in February, March, and April, and are now considerably warmer than in 2021 or 2022.

The most significant spatial features of year-to-date temperatures are the shift towards El Niño, warmth across much of the northern mid-latitudes, cooling in the Western USA, and several ocean hotspots. Year-to-date, 5.3% of the Earth’s surface has experienced average temperatures that are a local record high. In addition, none of the Earth’s surface has been record cold year-to-date.

Rest of 2023

2023 is on pace to be one of the warmest years yet observed. The surprisingly strong warming in March and April 2023, combined with the likelihood of a strong El Niño event, have increased the forecast for the rest of 2023. The statistical approach that we use, looking at conditions in recent months, now believes that 2023 is slightly more likely than not to become the warmest year on record (54% chance). Thought the uncertainty ranged has narrowed since April, the forecast probability is little changed from last month’s report, when the likelihood of a record warm year was estimated at 56%. If 2023 does not become the warmest year on record, then it would likely finish 2nd, 3rd, or 4th (combined chance 44%), with only a slight chance of a final ranking lower than 4th. The final ranking will depend strongly on how El Niño develops during the rest of the year.

In this assessment, we find it very likely that 2023 will result in the warmest year in the oceans ever measured (87% likelihood), boosted by global warming and the presence of El Niño. However, it is unlikely that the land average will also set an annual average record in 2023, with a 3rd place finish being the most likely outcome.

Even in the presence of a strong El Niño, 2023 would still be unlikely to exceed 1.5 °C (2.7 °F) above the preindustrial benchmark.

Absent an enormous volcanic eruption, or other exceptional intervening event, it is near certain that 2023 will become one of the warmest years on record.

Because of the lag between the development of an El Niño and its maximum impact on global temperatures, an El Niño that develops during 2023 is likely to have an even larger warming effect on global mean temperature in 2024 than 2023.

Likelihood of final 2023 ranking:

  • 1st place (54 %)
  • 2nd or 3rd place (26 %)
  • 4th place (18 %)
  • 5th place (1 %)
    • Top 5 overall (> 99 %)

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