Incredibly warm waters continue to build across the equatorial Pacific, and the El Niño event of 2015 has just set a record for the warmest waters ever observed in the equatorial Pacific over a 1-week period. Sea-surface temperatures (SSTs) in the Pacific’s Niño3.4 region, between 90°W and 160°E longitude and 5° north/south latitude, are considered the benchmark for rating the strength of an El Niño event.

The weekly departure of SST from average in this region hit +3.0°C (5.4°F) over the past week, NOAA announced in their November 16 El Niño update. This exceeds the previous 1-week record warmth in the equatorial Pacific of 2.8°C above average set during the week of November 26, 1997; accurate El Niño records extend back to 1950.

However, the standard measure for the strength of an El Niño event is the three-month average Niño 3.4 SSTs, and the El Niño of 2015 is not yet officially considered the strongest on record. The August-September-October 2015 three-month average Niño 3.4 SSTs were 1.7°C above average, good for only the 2nd warmest on record, behind 1997.

Judging from the trajectory of SST anomalies in Figure 1, though, it is likely that one of the late-year three-month average Niño 3.4 SST values in 2015 will end up upending 1997's record warmth and claim for the 2015 the title as strongest El Niño event on record.

http://www.wunderground.com/blog/JeffMasters/el-nio-of-2015-hits-alltime-record-strength-for-a-1week-period