Scientists are wondering what is happening over Antarctica and where are the noctilucent clouds. Noctilucent clouds or polar mesospheric clouds are the highest occurring cloud types (form about 50 miles or 80 Km above the Earth's surface). They form in the Mesosphere and are thin clouds made up of ice crystals that form from left over fine dust from meteors. Because they are so high up in the sky, you see them when the sun is low or almost nighttime. The form during the summer months over the north and south poles. That is when it is coldest that high up in the sky (in the mesosphere).
NASA researchers are wondering why are they not seeing them over Antarctica. They tend to see them by mid November but none have been detected. Scientists are also noticing that the ozone hole is the largest it's been in December and there are very cold temperatures at the surface being reported for this time of year (remember it Summer is starting in the Southern Hemisphere).
This article from SpaceWeather.com describes a bit more in detail what are scientists noticing.