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."