It's true that some people who live in warmer climates do tend to get less colds and flu viruses than people who live in colder climates.
But it's not because it's warmer there and colder in the other climates.
Cold weather doesn't cause colds or flues since you have to be infected with the virus to catch a cold or flu.
But people who live in warmer climates get more sunlight than people in colder climates and the sunlight helps to boost a persons immune system which helps to prevent the cold and flu viruses from affecting the person as much.