Watching the global thermometer - year to date GISTemp with a very hot October 2015

Wow! I knew that the Japan Meteorological Agency showed a big jump in October, and I expect GISS was doing some double and triple checking of the GISS data. October is the hottest October on record by a country mile. A whopping 1.04 °C above the 1951-1980 mean. This is the first time any month has an anomaly greater than 1 °C above the 1951-1980 mean (h/t Joe Stepansky).

Every month since March, I've posted a chart of the progressive year-to-date global average surface temperature, from GISS. This is the update with October included. I'll repeat the explanation with each update and add what seem to be things to watch.

Worth noting: Hottest October on Record by 0.18 °C

• 2015 is still hottest on record so far, and moving ahead of other years.
• The progressive year to date average up to and including October is 0.82 °C above the 1951-1980 mean, up from 0.81 °C to September.
• October was an average of 1.04 °C above the 1951-1980 mean and is the hottest October on record, after October last year (0.86 °C).
• June this year was the hottest June on record. 
• The highest anomaly this year is now October, at 1.04 °C.
• The lowest anomalies this year so far were April, now 0.73 °C, and August now also 0.73 °C above the 1951-1980 mean.
• To drop below the hottest year on record, 2014 (0.75 °C), the average anomaly for the next three months would need to be around 0.41 °C, which seems almost impossible. Especially given the El Niño and the fact that the lowest anomaly so far this year was 0.73 °C. 

Explaining the chart

The chart is a progressive year to date average, or running mean, for all years from 1995 to the present. What that means is for January each year, it just shows the anomaly for January. For February it shows the average of January and February for each year. For March, its the average of the monthly anomaly from January to March.

If you look at December, each year shows the annual average temperature for the full year. For November, each year has the average for the year up to November, not including December. (As before, I've made it extra large because of all the fine detail.)

Data Source: NASA GISS - GHCN-v3 1880-09/2015 + SST: ERSST v4 1880-09/2015

2015 is tracking above all other years, and rising. The years to watch were 2014, 2010 and 2005. I've plotted them with slightly thicker lines so they stand out more easily.

The coldest year of the lot was 1996, which still ended up being 0.35 °C above the 1950 to 1981 average.  The next time someone tries to tell you that "it hasn't warmed since 1996" then show them this chart :)

Below is the global mean surface temperature chart with 2015 the average to October, which is 0.85 °C above the twentieth century mean.

Data Source: NASA GISS - GHCN-v3 1880-09/2015 + SST: ERSST v4 1880-09/2015

Related updates

• YTD including March
• YTD including April
• YTD including May
• YTD including June
• YTD including July
• YTD including August
• YTD including September

Some charts showing how temperatures evolved in previous El Niño years can be seen in this article: Why Christopher Monckton is getting nervous about global temperature.
[Update] Here's an update to the GISTemp chart for El Niño years from that article. I had to extend the y axis to fit the October data. (In past years, GISTemp peaked in February/March the second year of the El Niño. It will probably not be till somewhere between January and April next year that lower troposphere temperature anomalies will peak.):

Here is the link to the table for the Year to Date chart.