How hot was June 2023?
June 2023 mean temperature anomaly and distribution
Figure 1 shows the June temperature anomalies by ENSO status. The Oceanic Niño Index (ONI), which is used by NOAA to define ENSO status, looks at the three-month average temperature in the Nio3.4 region that is centered on that month. We need at least five months in a row with temperatures that are more than 0.5°C [0.9°F] above the working "normal" for El Niño. In the same way, La Niña events have at least five months in a row that are cooler than usual by more than 0.5°C (0.9°F). Technically, we don't know if June 2023 will be an El Niño, but NOAA's June 2023 Global Climate Report says that it is emerging.
Weak El Niño conditions that emerged in May strengthened, as above-average sea surface temperatures returned to the equatorial Pacific Ocean.
Given the record anomaly for June 2023, it isn’t surprising that El Niño was emerging. Also from the NOAA report:
June 2023 set a record as the warmest June for the globe in NOAA's 174-year record. The June global surface temperature was 1.05°C (1.89°F) above the 20th-century average of 15.5°C (59.9°F). This marked the first time a June temperature exceeded 1°C above the long-term average.
When we think of a global temperature that is above normal, we tend to think that everywhere is warmer, but the mean is not the same as the distribution. Figure 2 is a map of temperature anomalies from NASA for the month of June 2023 that shows how anomalies are distributed.
Overall, we saw above-average temperatures, but not everywhere. For example, the east coast of the U.S. was slightly cooler. On the other hand, from the NASA report
With an average temperature 2.5°C above average, the United Kingdom had its warmest June since records began in 1884.
How does June 2023 fit into the big picture? Figure 3 is a revised version of the graph in the post called “Three Trends of Climate Change.” Note that ENSO status needs a three-month average focused on a given month. This is why June 2023 is not on this graph, but May 2023 is. June's temperature difference was 1.89°F, which isn't a record but is still in the top 10. The next report for July should be interesting, given that new records are being set (see Quick Takes and Random Stuff).
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Data
ENSO data from Oceanic Niño Index (ONI)
June Global Temperature anomalies from NOAA NCEI