Monday was the world's hottest day on record, exceeding an average of 17 degrees Celsius (62.6 degrees Fahrenheit) for the first time, according to initial measurements taken on Tuesday by US meteorologists.
The average daily air temperature on the planet's surface on July 3 was logged at 17.01 °C by an organisation attached to the US National Oceanic and Atmospheric Administration (NOAA).
This measurement surpasses the previous daily record (16.92 °C) set on July 24 last year, according to data from NOAA's National Centers for Environmental Prediction going back to 1979.
The world's average air temperature, which fluctuates between around 12 °C and just under 17 °C on any given day over the year, averaged 16.2 °C at the beginning of July between 1979 and 2000.
The record has yet to be corroborated by other measurements, but could soon be broken as the northern hemisphere's summer begins.
The average global temperature typically continues to rise until the end of July or beginning of August.
Even last month, average global temperatures were the warmest the European Union's Copernicus climate monitoring unit had ever recorded for the start of June.
Temperatures are likely to rise even further above historical averages over the next year with the onset of an El Nino weather phenomenon in the Pacific Ocean, which the World Meteorological Organization confirmed on Monday is now underway.
In addition, human activity –- mainly the burning of fossil fuels -– is continuing to emit roughly 40 billion tonnes of planet-warming CO2 into the atmosphere every year.