How hot was July 2023?

and how historic was it really?

There have been numerous claims in the news regarding record-breaking global temperatures in July 2023; however, this is somewhat misleading. Here's the full story: First, Figure 1 represents the July historical temperature anomaly. It was certainly a record-setting year for July, on the order of 0.75 °F above the previous record anomaly. It should be noted that ENSO status will not be formally determined for some months. How does this compare to all months?

Figure 1: Temperature anomalies for the month of July in °F.

Figure 2 shows the anomalies for all months. The last month in black is July 2023. It's worth noting that it might not even be a top ten anomaly month. Certainly, a 2 °F anomaly is worth noting, as it doesn’t happen that often. So, what's the big deal about July?

Figure 2: Temperature anomalies for all months in °F.

The media chose to focus on the actual temperature, and for good reason due to the impact on human health. July is the warmest month of the year, and when combined with a large enough anomaly, you have a record temperature. Take a look at Figure 3. The black line represents the year 2023. Earlier in the month, a large anomaly set a monthly temperature record. If you look at the gray line in January, you will notice similar daily abnormalities that correlate to the peak anomaly in Figure 2. We should mention that we appear to have broken single-day anomalies slightly in July.

Figure 3: Daily global surface temperature. From https://climatereanalyzer.org/clim/t2_daily/

A quick digression Why is July the warmest month if these are global temperatures? Wouldn't the north and south balance out? The key point here is that these are surface temperatures, and the global north has more land mass than the global south (see Figure 4). Given the same solar radiation, for example, 2 meters over cool ocean water will be lower than 2 meters above land.

Figure 4: NASA map of temperature anomalies for July 2023 in °C. From https://data.giss.nasa.gov/gistemp/maps/

Finally, keep in mind that the global average temperature is just that: a mean. How is that dispersed globally? Figure 4 displays how anomalies differ around the world. The July 2023 Global Climate Report also points out that

Globally, July 2023 set a record for the highest monthly sea surface temperature anomaly (+0.99°C or +1.78°F) of any month in NOAA's 174-year record. July's sea surface temperature anomaly was 0.07°C (0.12°F) higher than the previous all-time record-high anomaly set in June 2023.

Now, there is a reason to talk about record global temperatures, as they do impact human health. Record anomalies in January aren't as dangerous as record anomalies in July, although we should acknowledge that July 2023 was not a record in terms of anomalies. With El Niño on the way, we could see a new anomaly record set before the end of the year. Of course, the narrative will be different, as a warmer winter for Europe would be a plus this year given the country's natural gas problems.

Let me conclude by noting that I am not trying to downplay the significance of July 2023. The temperatures did set new records. The climate is warming and will continue to warm. My purpose is to place the month in its proper historical context.

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Data

ENSO data from Oceanic Niño Index (ONI)

June Global Temperature anomalies from NOAA NCEI