Why can't the weather make its mind up??

Well the weather at the moment is so frustrating!!!! I never know what to put on the kids. One minute it is windy and rainy so I'm getting out the wellies and the winter coats. Then when we are out and about the sun decides to come out of hiding and make an appearance, now the kids are sweltering and so am I. It feels like I need to take a second outfit out with me just incase. What happened to proper seasons??