El Nino at 3.9C: the Met Office puts the heat record in 2027, and the warning arrives now

The useful part of this forecast is the calendar rather than the peak. The event was declared in early June and is expected to top out in November ^[7][8], about five months from declaration to maximum ^[26], and the global temperature consequence lands the year after, because the heat released from the Pacific reaches the atmosphere on a delay ^[4]. That is why the Met Office's Nick Dunstone points at 2027 rather than 2026 for the record ^[3]. Physical inputs rarely announce themselves that far ahead of the invoice.

The distance still to travel is worth stating in plain numbers. The Pacific is running about 2.6C above a rolling 30-year average on the Climate Brink dashboard, which uses NOAA data ^[2], while the forecasts that dashboard aggregates put the November peak at 3.9C ^[8]. That is a further 1.3C in roughly a quarter ^[23]. An El Nino is declared at 0.5C above baseline ^[9], so a 3.9C peak would sit close to eight times the definitional threshold ^[24] and 0.9C above the 3C recorded in 2015 ^[25]. Adam Scaife, who runs long-range forecasting at the Met Office, puts a typical event at 1C to 2C and calls 2C already a really big one ^[13]; the current reading has passed that mark by 0.6C with months of warming still in the forecast ^[22].

There is a real spread inside the reporting, and it is not decorative. Scaife told the BBC to expect something over 3C ^[1]. The aggregate says 3.9C ^[8]. The 0.9C between those two figures is nearly twice the anomaly needed to call an El Nino at all ^[21], and the two ends of that range do not imply the same losses for anyone buying cover or grain forward.

The regional signature is the part already usable. El Nino reliably dries Southeast Asia, Australia, southern Africa and northern Brazil while wetting the Horn of Africa, the southern United States, Peru and Ecuador ^[14]. Scaife expects severe drought in South America and the West Pacific ^[15], and increased rainfall and storminess in the United Kingdom around November ^[16]. His framing matters more than any single region: these are long-term persistent conditions, not a short-term weather forecast ^[18].

One caution against filing 2027 as an outlier. Both 1998 and 2016 were records when they happened, and both have since dropped down the rankings as warming makes record heat more likely ^[12]. Last year finished third ^[11]. An El Nino record is a spike riding a rising line, which means the year the Met Office expects to break the record is a reasonable preview of an ordinary year later in the decade, not a number to smooth out of a baseline. Scaife calls the event unprecedented and says he has never seen a signal this intense in the model output ^[6]; that is a statement about the forecast, and the observed peak in November is what will test it.