Weekly Global Climate Pulse: Thursday, October 22, 2026

By Paul Harrison, Orbis Weather

At a glance

El Niño has reached record strength on several agency measures, and the world’s oceans set a September warmth record.

Data issue dates: NOAA CPC ENSO discussion October 8 and weekly update October 19; JMA October 9; Australian Bureau of Meteorology (BoM) October 13; Copernicus September bulletin October 12; NOAA NCEI September report October 9; NSIDC sea ice analysis October 7; US Drought Monitor October 15 (valid October 13). Only the CPC weekly update and BoM figures are from the past ten days; the rest are monthly figures issued earlier in October.

• ENSO: BoM’s weekly relative Niño3.4 index reached +2.81°C (+5.06°F) for the week ending October 11, its highest on record (BoM, October 13).
• Oceans: NOAA NCEI put September’s global ocean surface anomaly at +1.10°C (+1.98°F) above the 20th-century average, the highest for any month on record (NCEI, October 9).
• Temperatures: September 2026 was the second-warmest September globally, after 2023 (Copernicus, October 12; NCEI, October 9).
• Sea ice: Antarctic sea ice fell to record-low daily extent for the time of year from October 2 (NSIDC, October 7).
• Drought: 53.73% of the Lower 48 was in drought, affecting 97.0 million people (Drought.gov, map valid October 13).
• Records: Copernicus reported the Niño 3.4 region’s September sea surface temperature as the highest monthly value in its dataset (October 12).

El Niño and La Niña

A strong El Niño is under way and still strengthening. NOAA’s Climate Prediction Center (CPC) keeps an El Niño Advisory in effect. Its October 8 synopsis reads: “El Niño continues to strengthen, with a strong-to-very strong El Niño likely through January-March 2027.”

*CPC defines a historic event as a three-month RONI of +2.5°C (+4.5°F) or more, beyond any El Niño since 1950. CPC expects El Niño to persist through March–May 2027.

JMA says El Niño conditions “have reached its strongest intensity on record since this September”, beating the December 1997 NINO.3 record of +3.6°C (+6.5°F). The World Meteorological Organization (WMO) forecasts an October–December Niño 3.4 anomaly of about +3.7°C (+6.7°F), above the previous record of +2.6°C (+4.7°F) in 2015–16 (October 8).

In the Indian Ocean, BoM still rates the Indian Ocean Dipole as neutral. Its index was +0.88°C (+1.58°F) for the week ending October 11, the fifth week above the +0.4°C (+0.72°F) threshold. BoM says a positive event “is likely to develop”; WMO expects the positive IOD to peak in October.

Oceans and global temperatures

September was the warmest September on record for the global ocean surface and the second warmest for air temperature. These are the latest monthly figures, issued October 9–12.

Copernicus put the average sea surface temperature for 60°S–60°N at 21.05°C (69.89°F) in September. That beat the September 2023 record of 20.92°C (69.66°F). In the Niño 3.4 region, the September average was 29.70°C (85.46°F), an anomaly of +2.99°C (+5.38°F). Copernicus reported waters 6–7°C (11–13°F) above average near the Peruvian coast.

Global surface air temperature averaged 16.27°C (61.29°F) in September, according to Copernicus. That was 0.11°C (0.20°F) below the September 2023 record.

Source: Copernicus C3S ERA5 monthly surface air temperature pages, May–September 2026.

The 12 months from October 2025 to September 2026 averaged +1.50°C (+2.70°F) above pre-industrial levels (Copernicus). Western Europe had its joint-warmest September, at +2.51°C (+4.52°F) against 1991–2020.

NOAA NCEI also ranked September second warmest, at +1.33°C (+2.39°F) above the 20th-century average. It ranked January–September second warmest and called 2026 “very likely” a top-five year, with second warmest most likely.

Sea ice

Antarctic sea ice is at or near record lows for the time of year, while Arctic ice ended the melt season low but above its 2012 record. The latest NSIDC analysis is dated October 7.

NSIDC’s Arctic September average was 1.6 million km² (618,000 sq mi) below the 1981–2010 average. NSIDC called its September 23 minimum and maximum figures “a preliminary announcement”. The two agencies use different satellite records and baselines, so their values differ.

Since the peak, Antarctic extent “sharply declined”, NSIDC reported on October 7. By early October, Arctic freeze-up had been “rapid”. NSIDC noted that AMSR2 satellite data processing was paused, with resumption expected after October 21.

Drought

Over half of the Lower 48 remains in drought, with gains in the Southeast offset by losses along the lower Mississippi and in the Midwest. These figures come from last week’s US Drought Monitor map; this week’s map is due at 8:30 a.m. ET today.

Abroad, FEWS NET said on October 6 that South Sudan and Karamoja in Uganda are “on track for their driest year on record”. Brazil’s Amazonas state declared an emergency in 36 municipalities, including Manaus, on October 10; Manaus had 44 mm (1.7 in) of rain in July–September against a normal 202 mm (8.0 in) (Rio Times, October 11). In Europe, the EU’s drought observatory reported that “drought conditions remained critical in most of Europe” in late September.

Records and milestones

This month’s records cluster around El Niño and ocean heat. Figures for most are given in the sections above.

Copernicus also reported a daily global sea surface temperature record of 21.11°C (70.00°F) on August 24–25, in its August bulletin.

What to watch

The next big markers are JMA’s and CPC’s November ENSO updates, which will show whether El Niño has moved further into record territory.

About this report

The Weekly Global Climate Pulse tracks climate indicators: ocean-atmosphere drivers, ocean and air temperatures, sea ice, drought and records. Day-to-day weather is covered in other Orbis Weather reports. Agencies compare against different baselines. Copernicus uses 1991–2020 for recent climate and 1850–1900 as a pre-industrial reference; NSIDC uses 1981–2010; NOAA NCEI often uses the 20th-century average. Figures from different agencies are therefore not directly comparable. Many indicators update monthly, and recent values can be revised.

Glossary

• ENSO: El Niño–Southern Oscillation, the cycle of warming (El Niño) and cooling (La Niña) of the tropical Pacific.
• Niño-3.4: a central-eastern Pacific box whose temperature anomaly is the main gauge of ENSO.
• RONI: the Relative Oceanic Niño Index, CPC’s three-month ENSO index, which adjusts for warming of the wider tropics.
• Indian Ocean Dipole (IOD): the temperature difference between the western and eastern tropical Indian Ocean.
• Sea ice extent: the ocean area with at least 15% ice cover.

Frequently asked questions

Is this the strongest El Niño on record? On some measures, yes. JMA and BoM both report record values for their indices. CPC rates a “historic” event, beyond any since 1950, as more likely than not for October–December.

When will El Niño peak? WMO expects a peak in December 2026 and persistence through February 2027. CPC expects El Niño to last through March–May 2027.

Will 2026 be the warmest year on record? Probably not, on NOAA NCEI’s assessment. NCEI calls 2026 “very likely” a top-five year, with second warmest the most likely outcome.

Why do NSIDC and Copernicus give different sea ice figures? They use different satellite records and different baselines. Both agree that Antarctic ice is among the lowest on record.

Is US drought easing? It is mixed. The latest map showed improvement in the Southeast and Southwest but worsening along the lower Mississippi and in parts of the Midwest.