In winter, the temperature of New York is the lowest, and the temperature of London is a litter higher. In summer, New York is about five degree centigrade and London is seven to eight degree centigrade. New York is hotter than London, New York is about thirty degree centigrade and London is about twenty five degree centigrade. I think the reason is the total annual hours of sunshine for New York are higher than London. I didn’t mention Sydney, because Sydney is a city in the southern hemisphere, the seasons there are opposite. On the whole, Sydney is much hotter than the other two cities, because Sydney close to the equator, the total annual hours of sunshine for Sydney is much higher than higher the other cities. The temperature of London
