It would be winter in Canada when it is summer in Australia. First off, they are on opposite sides of the world -- Australia is in the southern hemisphere, the earth is tilted to the sun, which of course would cause the hot weather. Canada is in the northern hemisphere, which is opposite and further away from the sun.
It is winter in Montreal when it is summer in Sydney. This is because when the southern hemisphere, where Sydney is located, is tilted toward the Sun, the northern hemisphere, where Montreal is located, is tilted away from the Sun.
