Average surface temperature reached 16.38°C, or 0.5°C above the previous record in September 2020.

Last month was roughly 1.75°C warmer compared to the pre-industrial period. It was also  0.93°C warmer than the 1991-2020 baseline which is used as a practical tool for climate sensitive sectors like agriculture.

The heat is on

WMO said this continues an extended streak of extraordinary land and sea-surface temperatures and is an ominous signal about the speed with which greenhouse gases (GHG) are changing the climate.

"The temperature anomalies are enormous – far bigger than anything we have ever seen in the past. Antarctic winter sea ice extent was the lowest on record for the time of year,” said Petteri Taalas, the agency’s Secretary-General.

“What is especially worrying is that the warming El Niño event is still developing, and so we can expect these record-breaking temperatures to continue for months, with cascading impacts on our environment and society,” he added.

A ‘dubious honour’

Samantha Burgess, the C3S Deputy Director, stressed that September 2023 is one for the record books.

“This extreme month has pushed 2023 into the dubious honour of first place – on track to be the warmest year and around 1.4°C above pre-industrial average temperatures,” she said.

With the COP28 UN climate change conference taking place in Dubai next month, “the sense of urgency for ambitious climate action has never been more critical,” she added.

Climate conference looms

WMO uses the C3S data for its State of the Global Climate monitoring reports. The UN agency will release the 2023 provisional report at the start of COP28.

Countries will meet to speed up progress towards the shift to clean energy in efforts to limit global temperature rise to 1.5°C above pre-industrial levels, in line with the Paris Agreement on climate change.

WMO said the fact that an individual month, or year, exceeds the 1.5 °C limit does not mean that the accord has been breached because the level it mentions refers to long-term warming over many years.