The Sun stands for anything but snow or rain!
The WeatherPlanner forecast predicts precipitation (rain and snow) and temperature. Certain days are marked by the sun icon because no significant precipitation is expected for that time period.
The forecast does not predict when the skies will be clear however WeatherPlanner places a value on dry predictions. How much sun appears in the sky depends on the amount of cloud cover and the speed at which it moves -- two highly variable aspects of weather forecasting.
Short-range forecasts can show clouds and sun. The WeatherPlanner forecast does not include cloudy days and sunny days because cloud cover is too variable to predict on the long range.
So wherever you see the sun icon think of the days as mostly dry, with a good possibility of sunshine and no precipitation