Last month was the warmest October on record, marking the sixth consecutive month of record temperatures. The record heat comes as countries try to reach a climate pact at the end of the month in Paris.
"The combined average temperature over global land and ocean surfaces for October 2015 was the highest for October in the 136-year period of record, at 0.98°C (1.76°F) above the 20th century average of 14.0°C (57.1°F)," the US National Oceanic and Atmospheric Administration (NOAA) said on Wednesday.
Eight months this year have broken records, but October was "the greatest departure from average for any month in the 1630 months of recordkeeping," NOAA said.
The October average temperature on land hit 1.33°C (2.39°F) above the 20th-century average.
Global water surface temperatures also set records for October at 1.53 Fahrenheit (0.85 Celsius) above the 20th century average, in part due to El Nino.
This year is set to be the warmest on record.
The data comes as world leaders are set to meet for two weeks of make-or-break climate talks in Paris at the end of November to cut greenhouse gases.