What is the weather in Melbourne and Sydney like at the end of July?

We are planning to go to Melbourne and Sydney the end of this month. I know that the temperature is around 12-15 degrees Celsius. But does it feel colder because it's wet, rains a lot, and windy? Also, is it always really gloomy in the winter? Overall, do you think it'd be a good tourist destination if we go in the winter? I really hate cold and gloomy weather. I prefer the warm and sunny.