The average for the four months to the end of April is 1.21 °C, which is 0.38 °C higher than any previous January to April period. The previous highest was last year, which with the latest data had an anomaly of 0.84 °C.
Longest stretch of hottest months in the record
This is the seventh month in a row of "hottest months", all of which had an anomaly more than one degree Celsius above the 1951-1980 mean.
This hasn't happened before in the record since at least the 1950s. Earlier times probably aren't sufficiently accurate on a month by month basis to say. I didn't check back that far and, in any case, pre-1950s temperatures would probably have been hotter at some time in the last couple of millenia. What that means is that it's probably more than 7,000 years since there was a similar run of hottest months on record. That is, not since the Holocene climatic optimum (and it's probably hotter now than it was back then).
Below is a chart of the month of April only:
|Figure 1 | Global mean temperature anomaly - month of April only. Data source: GISS NASA.|
|Figure 2 | Global mean surface temperature for El Nino years. Data source: GISS NASA|
Once again it was the high latitudes in the northern hemisphere that had the highest anomalies this month.
|Figure 3 | Map showing mean surface temperature, anomalies for April, from the 1951-1980 mean. Source: GISS NASA|
Below is March for comparison:
|Figure 4 | Map showing mean surface temperature, anomalies for March, 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 April. This year is tracking well above 2015, probably mainly because of the current (fading) El Niño. To drop below the average for 2015, the average for the next eight months would need to be less than 0.62 °C:
|Figure 5 | Global mean surface temperature, progressive year to date to March 2016. Data source. GISS NASA|