The average global temperature reached 17.01C, surpassing the August 2016 record of 16.92C as heatwaves sizzled around the world.
The southern United Stats has been suffering under an intense heat dome in recent weeks.
In China, an enduring heatwave continued, with temperatures above 35C.
North Africa has had temperatures near 50C.
And even Antarctica, currently in its winter, registered anomalously high temperatures.
Ukraine's Vernadsky Research Base in the white continent's Argentine Islands recently broke its July temperature record with 8.7C.
"This is not a milestone we should be celebrating," climate scientist Friederike Otto of the Grantham Institute for Climate Change and the Environment at Imperial College London, said.
"It's a death sentence for people and ecosystems."
Scientists said climate change, combined with an emerging El Nino pattern, were to blame.
"Unfortunately, it promises to only be the first in a series of new records set this year as increasing emissions of (carbon dioxide) and greenhouse gases coupled with a growing El Nino event push temperatures to new highs," Berkeley Earth research scientist Zeke Hausfather said.
29°C