According to the World Meteorological Organization (WMO) the global temperatures were set to rise 1° Celsius above the pre-industrial era in 2015, said a statement issued by the WMO.
This is due to a combination of a strong El Niño and human-induced global warming, added the statement.
The years 2011-2015 have been the warmest five-year period on record, with many extreme weather events - especially heatwaves - influenced by climate change, according to a WMO five-year analysis.
"The state of the global climate in 2015 will make history as for a number of reasons," said WMO Secretary-General Michel Jarraud.
"Levels of greenhouse gases in the atmosphere reached new highs and in the Northern hemisphere spring 2015 the three-month global average concentration of CO2 crossed the 400 parts per million barrier for the first time. 2015 is likely to be the hottest year on record, with ocean surface temperatures at the highest level since measurements began. It is probable that the 1°C Celsius threshold will be crossed," said Mr Jarraud. "This is all bad news for the planet."
Greenhouse gas emissions, which are causing climate change, can be controlled. We have the knowledge and the tools to act. We have a choice. Future generations will not."
"Added to that, we are witnessing a powerful El Niño event, which is still gaining in strength. This is influencing weather patterns in many parts of the world and fuelled an exceptionally warm October. The overall warming impact of this El Niño is expected to continue into 2016," said Mr Jarraud.
WMO issued its provisional statement on the status of the climate in 2015, and an additional five-year analysis for 2011-2015, to inform negotiations at the U.N. Climate Change Conference in Paris.