The El Nino weather phenomenon, which triggers higher global temperatures, is set to continue throughout 2023 and will be "at least of moderate strength", the United Nations said on Tuesday.
El Nino is a naturally occurring climate pattern typically associated with increased heat worldwide, as well as drought in some parts of the world and heavy rains elsewhere.
The US National Oceanic and Atmospheric Administration announced on 8 June that El Nino had arrived, warning that it "could lead to new records for temperatures".
The NOAA feeds into the UN's World Meteorological Organization, which for its part declared the onset of El Nino conditions on Tuesday, saying there was a 90-per cent probability of the phenomenon continuing during the second half of 2023.
"It is expected to be at least of moderate strength," the WMO said, noting that El Nino's effect on global temperatures is usually felt most strongly within a year of its onset -- in this case in 2024.
"The onset of El Nino will greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean," said WMO secretary-general Petteri Taalas.
Since 2020, the world has been affected by an exceptionally long La Nina -- El Nino's cooling opposite -- which ended earlier this year.
And yet, the UN has said the last eight years were the warmest ever recorded, despite La Nina's cooling effect stretching over nearly half that period.
Without that weather phenomenon, the warming could have been even worse.
"The declaration of an El Nino by WMO is the signal to governments around the world to mobilise preparations to limit the impacts on our health, our ecosystems and our economies," said Taalas.
"Early warnings and anticipatory action of extreme weather events associated with this major climate phenomenon are vital to save lives and livelihoods."