weather similarity scores

Just an idle thought, but don't you think it'd be useful for weather forecasts to have a similarity score? Basically just a one number reference that gave you an idea of how close today's forecast was to yesterday's weather (or tomorrow to today, etc...). I'm horrible at relating a certain temperature (especially Celsius) to a particular type/amount of clothes I need to wear. But if I had a number that had today's weather as a frame of reference (without haven't to look up the previous high/low, etc...), that would be tremendously handy. It should probably factor in winds and humidity, but precipitation could still just be percentage chance of rain/snow. Know of anything like this?