Living in a warmer climate doesn't always mean that you'll never get colds, flues or other viruses and never get sick.
But yes living in a warmer climate can mean you stay healthier because when you're in a warmer climate you're usually outside more and not stuck inside the house staying warm.
When you're stuck inside the house around other people viruses tend to hang out inside the house and then spread from person to person.
Living in a warmer climate is usually better for your mood as well because cold weather and dreary days can bring a persons mood down and fuel anxiety.
People are usually much happier if they can experience more sunshine and they also get the benefit of the Vitamins from the sun more so that also makes the person more healthy.