The phrase "wacky weather" refers to unusual, unpredictable, or strange weather conditions. It means that the weather is not following the usual patterns or expectations. Full definition
We've been having wacky weather here too, it was in the 90s not that long ago and now we're having trouble reaching the 70s! (have-clothes-will-travel.com)
However, the science behind the link between warming in the Arctic and wackier weather in the midlatitude regions like the United States, Europe and much of Asia is far from proven. (scientificamerican.com)