Here's the thing with those apps, include the one included on the iphone - even if there is chance of snow or rain at 1am in the morning, the day will show snow or rain. So many partly cloudy fine days will happen the majority.
No knowledge of the algoritm used but certainly check the hourly the day before.
Unless you are hiking in the high peaks. If a report says only 10% chance of rain in a day, that mean 100% in the high peaks. Always. May not be heavy, but it will occur.