A Seasonal Dilemma

It's called "What to Pack?"  When the temperature goes from 70 degrees one day to 40 degrees the next day, it's hard to know how to fit an appropriate wardrobe in a backpack.  Will I need short sleeves or a sweater and coat?  Layers tend to be the answer this time of year.  A look at the forecast this morning shows that it may be leveling off for the rest of the month.  We'll see!