What is the average temp in Antarctica in winter?

Antarctica is a large continent, as large as US and Mexico combined, which covers 10% of the earth's surface. Since it's in the Southern Hemisphere, the seasons are reversed, meaning that the coldest days are in the Antarctic winter: June-September.

So giving you an average temperature of that much landmass won't give you much information.

Antarctica is roughly 30 degrees F colder than its counter-part in the Northern Hemisphere, because it's land. (Frozen ice covers the North Pole location.)

The coldest temperature officially recorded in Antarctica was recorded at Vostok Station in 1983: -129 degrees F. However, an informal record of minus 132 degrees F was reached in 1997. (See link, below.)

As well, there are parts of Antarctica, in the Antarctic Peninsula, where it's warm enough to rain.