What is the meaning of "a naughty boy" in this passage?

Weather is basically the way that the atmosphere is behaving, mainly with respect to its effects upon life and human activities. Perhaps it is hot, dry and sunny today where you live, but in other parts of the world it is cloudy, rainy or even snowy. We will change our clothes into shorts in the hot sunny day, while we often choose to stay indoors or change a jacket when it is cold and cloudy outside. Weather is like a naughty boy. It changes from day to day and from place to place. The weather forecast will tell us the condition of weather in advance. We needn’t to be worried about what to wear next day.
    Compared with weather, climate is much like an elder sister. It is more stable. It describes the weather condition of a particular graphic area over a specified time. Climate tells us what it is usually like in the place we live. It is the result of many physical actions on land, in the atmosphere, in the oceans and in space. They usually change slowly over hundreds of years. With the computer programs, the scientists can detect how the climate changes in years ahead. Data shows the earth has warmed about 1 centigrade in the past 100 years, and the temperature still continues to rise as the result of the greenhouse gases the human beings produce in the atmosphere. Some scientists predict that global warming caused by the greenhouse effect would cause more natural disasters like droughts and floods. So the study of climate is the same important as that of weather, because it also has large influence on people’s life.