Antarctica has exceeded 20C for the first time, after researchers logged a temperature of 20.75C on an island off the coast of the continent.
Brazilian scientist Carlos Schaefer told AFP they had "never seen a temperature this high in Antarctica".
But he warned the temperature, logged on 9 February, was just one reading and not part of a long-term data set.
The continent also hit a record last week, with a temperature reading of 18.3C on the Antarctic Peninsula.
This latest reading was taken at a monitoring station on Seymour Island, part of a chain of islands off the same peninsula, at the northernmost point of the continent.
Although the temperature is a record high, Mr Schaefer emphasized that the reading was not part of a wider study and so, in itself, could not be used to predict a trend.
"We can't use this to anticipate climatic changes in the future. It's a data point," he said. "It's simply a signal that something different is happening in that area."
According to the UN's World Meteorological Organisation (WMO), temperatures on the Antarctic continent have risen by almost 3C over the past 50 years, and that about 87% of the glaciers along its west coast have "retreated" in that time.
Over the past 12 years the glaciers have shown an "accelerated retreat" due to global warming, it adds.
Last month was also Antarctica's warmest January on record.