June is cooler in 2017 but still the 4th hottest June on record

Summary: June 2017 was the fourth hottest June on record. The 12 months to June 2017 was the second hottest July to June period on record.

According to GISS NASA, the average global surface temperature anomaly for June was 0.69 °C, which is 0.10 °C less than the hottest June in 2016, making June 2017 the fourth hottest June in the record. It's the hottest June in any year when there was no El Nino.

Below is a chart of the average of 12 months to June each year. The 12 months to June 2017 averaged 0.91 °C above the 1951-1980 mean, which was 0.10 °C cooler than the 12 months to June 2016.

This makes it the second hottest July to June 12 month period on record.

Figure 1 | Global mean surface temperature anomaly for the 12 months to June each year. The base period is 1951-1980. Data source: GISS NASA

Next is a chart of the month of June only. This June was 0.69 °C above the 1951-1980 average and was the fourth hottest June on record. It was 0.10 °C cooler than June 2016, which was 0.79 °C above the 51-80 mean. 1998 and 2015 were both 0.78 °C above the 1951-1980 mean. If you consider that the surface temperature in June in 1998, 2015 and 2016 were affected by El Nino, then this June is the hottest June in a year without an ENSO event.

Hover over the chart to see the anomaly in any June:

Figure 2 | Global mean surface temperature anomaly for the the month of June only. The base period is 1951-1980. Data source: GISS NASA

ENSO year comparisons - another El Niño? Probably not.

In the chart below you can see the global mean temperature trend by month. It shows the strongest El Niño years since 1950, which were followed by a La Nina. I've included the 2015-17 period for comparison. The BoM ENSO update is now showing inactive, with no ENSO even likely this year.

Of the seven very strong, strong and strong to moderate El Ninos since 1950, there were only three that were followed by a La Nina (not including 2015-17, which I don't count). The chart spans a three year period. That is, for the 2015-16 El Niño and subsequent, it goes from January 2015 to December 2017, or would if the data allowed. (For a more detailed explanation see the HW articles: El Niño to La Niña years with more detail here.)

Figure 3 | Global mean surface temperature for strong or moderate/strong El Nino years that were followed by a La Nina. Also includes the 2015/16 El Nino for comparison. Data source: GISS NASA

Where was it hot?

In May it was very hot in much of Antarctica. It cooled right down there in June. Move the arrow at the left to the right to compare June with May.

Figure 4 | Maps showing mean surface temperature, anomalies for June and May, from the 1951-1980 mean. Data source: GISS NASA

Year to date chart

For the record, here is the year to date progressive chart. You need to understand what it is to make sense of it. The chart below shows the average temperature for the year at each point on each separate line on the chart. The topmost line is last year (2016). At January, the point is just the anomaly for January. At February, the point is the average anomaly for January and February. At June, it's the average of January to June inclusive - all the way to December, which is the average for the whole year.

So the 2017 year shows that the average for the period January to June is 0.94 °C. This is 0.16 °C lower than the average for the year was this time last year during the massive El Nino. The average over the entire 2016 year is 0.99 °C (the point marked for December on the 2016 line) so although it's not completely impossible for this year to be another hottest year, the next few months would have to be very hot for that to happen.

Figure 5 | Progressive year to date global mean surface temperature anomaly. The base period is 1951-1980. Data source: GISS NASA

The anomalies for the rest of the year would have to average at least 1.05 °C for 2017 to be hotter overall than last year. That seems highly unlikely. The anomalies would have to average 0.8 °C or less for 2015 to be hotter than 2017. That's not impossible.