“Winters tend to be milder in the Southern Hemisphere than in the North, and many of the factors that cranked up the heat across North America, Europe, and Asia in recent months are doing the same thing below the equator: Ocean temperature cycles like El Niño are in their warm phases, while greenhouse gasses from burning fossil fuels are accumulating in the atmosphere, warming the planet and changing its climate. So the hot winter across the Southern Hemisphere this year lined up with what scientists expected.”
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““The biggest difference between the Northern and Southern hemispheres as a whole is that the North contains more large continents with an Arctic Ocean, whereas the Southern features fewer large land areas, the Southern Ocean and then Antarctica,” Grose said.
The oceans act like shock absorbers for weather and have a moderating effect on the climate. The Southern Hemisphere, with proportionately more ocean than land, tends to have a less drastic swing between seasons than places above the equator. That also means that winters in the south start from a warmer baseline than winters in the north.
So countries like Brazil rarely get chilly weather in the winter. “It’s dry and mild,” said Fábio Luiz Teixeira Gonçalves, a professor of geosciences at the University of São Paulo. Temperatures typically range between 53°F and 78°F, but they have been about 3.6°F higher on average since May around São Paulo. Those higher average temperatures fueled more extreme heat.”
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“Hotter weather in the winter can have a lot of important consequences, even if temperatures don’t reach the triple-digit peaks of the summer. Plants, for instance, rely on temperature signals to time their life-cycles”
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“Cold temperatures also keep dangerous insects in check”
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“Warmer, drier winters also mean that there is less water recharging rivers and groundwater supplies, and thus less water available for agriculture the following season.”
https://www.vox.com/climate/23864998/heat-wave-south-america-brazil-australia-argentina-hemisphere-winter