Copernicus: September 2026 Was the Second-Warmest September Globally

September 2026 was the second-warmest September in the global ERA5 record, according to data from the Copernicus Climate Change Service (C3S). The global average surface air temperature was 16.27°C. That is 0.82°C above the 1991–2020 average for the month and 1.63°C above the estimated 1850–1900 pre-industrial average. The event period is September 2026, so it is complete as of 16 October 2026. The supplied GKToday report is dated 12 October 2026.

Key facts at a glance

Who produces the data

C3S and ECMWF

The Copernicus Climate Change Service (C3S) is implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF). ERA5 is a global atmospheric reanalysis dataset produced by ECMWF, and the ranking applies to that dataset.

What the baselines mean

The two comparisons answer different questions. The 1991–2020 average is the reference for the reported anomaly of +0.82°C. The 1850–1900 period is the estimated pre-industrial reference, against which September 2026 was +1.63°C.

A single month above 1.5°C relative to the pre-industrial baseline is not the same as the Paris Agreement's long-term temperature goal. That goal concerns sustained warming over a longer period. The Paris Agreement was adopted in 2015 under the United Nations Framework Convention on Climate Change.

El Niño and ocean temperatures

El Niño is the warm phase of the El Niño–Southern Oscillation. This recurring climate pattern involves changes in sea surface temperatures and atmospheric circulation across the tropical Pacific. The Niño 3.4 region is a central equatorial Pacific area used to monitor El Niño and La Niña conditions. Its September 2026 monthly sea surface temperature of 29.70°C was a record for the region.

The source says El Niño conditions were strengthening and were expected to intensify further. They could peak later in 2026 and continue into 2027. This is an expectation, not a completed outcome, so treat it as ongoing.

Across the extra-polar oceans between 60°S and 60°N, the September 2026 sea surface temperature averaged 21.05°C. This was the highest for September in the record. It beat the earlier September record of 20.92°C, set in 2023, by 0.13°C.

Europe and Antarctic sea ice

Europe had its third-warmest September, with an average land temperature of 16.26°C, and experienced unusually warm and dry conditions. A Copernicus-linked EU Space page also lists an item titled "September 2026 was the third-warmest September for Europe", dated 12 October 2026. Only the headline was available, so the figures here rest on the GKToday report.

Antarctic sea ice reached its third-lowest annual winter maximum in September 2026. Sea-ice extent is the area of ocean where sea ice covers at least a specified proportion of the surface.

Exam-relevant context

• Remember the distinction: the event is a September 2026 measurement; the report appeared in October 2026.
• "Second-warmest" means September 2023 remains the warmest September in the dataset.
• Know the full forms: C3S (Copernicus Climate Change Service) and ECMWF (European Centre for Medium-Range Weather Forecasts).
• Keep the baselines separate: 1991–2020 for the anomaly, 1850–1900 for the pre-industrial comparison.
• Do not treat one month's temperature as a breach of the Paris Agreement goal.

Limits of the available evidence

The 2026 figures come from one secondary report, GKToday. The original C3S bulletin was not among the supplied sources, so the numbers could not be checked against it here. The supplied Copernicus page about September 2024 describes a different year, when that month was +0.73°C above 1991–2020 and +1.54°C above the pre-industrial average. It should not be mixed up with the 2026 figures. The evidence does not say how often such records appear in exams.

Frequently asked questions

Which September was warmer than September 2026?

September 2023 was the warmest September in the ERA5 dataset. September 2026 was 0.11°C cooler.

Does 1.63°C above pre-industrial mean the Paris goal was breached?

No. The source says a monthly value above 1.5°C is distinct from the Paris Agreement's long-term goal, which concerns sustained warming over a longer period.

Practice MCQs

Question 1

Where did September 2026 rank among Septembers in the global ERA5 record?

1. Warmest
2. Second-warmest
3. Third-warmest
4. Coolest

Answer: Second-warmest — the report says September 2026 was the second-warmest September, behind September 2023.

Question 2

What was the global average surface air temperature for September 2026?

1. 16.26°C
2. 16.27°C
3. 21.05°C
4. 29.70°C

Answer: 16.27°C — this is the reported global surface air temperature for the month.

Question 3

September 2026 was 1.63°C above which reference average?

1. The 1991–2020 average
2. The estimated 1850–1900 pre-industrial average
3. The September 2023 value
4. The 2015 Paris Agreement average

Answer: The estimated 1850–1900 pre-industrial average — the +1.63°C anomaly is given against that period, while +0.82°C is against 1991–2020.

Question 4

What was the September 2026 monthly sea surface temperature in the Niño 3.4 region?

1. 16.27°C
2. 20.92°C
3. 21.05°C
4. 29.70°C

Answer: 29.70°C — the report calls this a record for the region.

Question 5

Which organisation implements the Copernicus Climate Change Service (C3S)?

1. European Centre for Medium-Range Weather Forecasts
2. United Nations Framework Convention on Climate Change
3. Indian Meteorological Department
4. World Meteorological Organization

Answer: European Centre for Medium-Range Weather Forecasts — the source says C3S is implemented by ECMWF.