Hottest May on record with year to date temperature

by Sou, Hot Whopper, June 13, 2016 

Yes, another "hottest" on record - this time for May 2016. According to GISS NASA, the average for May was 0.93 °C, which is 0.07 °C above the previous hottest May, in 2014. Last month is the first time in seven months that the GISTemp monthly anomaly is one degree Celsius below the average from 1951-1980.  This month the anomaly is the 9th highest for any month, lower than all anomalies from October last year, and lower than that for January 2007.

The average for the five months to the end of May is 1.15 °C, which is 0.29 °C higher than any previous January to May period. The previous highest was last year, which with the latest data had an anomaly of 0.86 °C.

There are now eight in a row of "hottest months" from October 2015 to May 2016 (that is, hottest October, hottest November etc.). All of the previous months had an anomaly more than one degree Celsius above the 1951-1980 mean. All of the previous months had an anomaly higher than any month outside of that October to April period. May this year had an anomaly of 0.93 °C, which is lower than the anomaly in January 2007 (0.96 °C).

Below is a chart of the month of May only. Hover over the chart to see the anomaly in any May:

Figure 1. Global mean surface temperature anomaly for the month of May only. The base period is 1951-1980. Data source: GISS NASA

Here is a chart of the average of 12 months to May each year. The 12 months to May 2016 was 0.16 °C hotter than the 12 months to May 2015:

Figure 2. Global mean surface temperature anomaly for the 12 months to May each year. The base period is 1951-1980. Data source: GISS NASA

El Niño no more

You can see the global mean temperature trend by month in the chart below, for recent El Niño years:

Figure 2. Global mean surface temperature for El Nino years. Data source: GISS NASA

There's probably at least a 50/50 chance of a La Niña forming this year, so this is a chart comparing all the strong El Niño years since 1950 that were followed by a La Niña. Not counting 2015/16, 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. 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. (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. Data source: GISS NASA

Where was it hot?

Once again the high latitudes in the Northern Hemisphere had high anomalies this month but not as high as last month. There's also some parts of Antarctica that were very, very hot (well, it's still rather cold down there, but much hotter than the 1951-1980 average).

Figure 4. Map showing mean surface temperature, anomalies for May, from the 1951-1980 mean. Source: GISS NASA

Below is April for comparison:

Figure 5. Map showing mean surface temperature, anomalies for April, from the 1951-1980 mean. Source: GISS NASA

Year to date average surface temperature

The chart below tracks the year to date. Each point on the plot is the average of the year to that month. For 2016, the last point is the average of all months to date including May. This year is tracking well above 2015, largely because of the El Niño. To drop below the average for 2015, the average anomaly for the next eight months would need to be less than 0.66 °C:

Figure 5. Global mean surface temperature, progressive year-to-date to May 2016. Data source. GISS NASA

http://blog.hotwhopper.com/2016/06/hottest-may-on-record-with-year-to-date.html