Let's say I didn't check the weather yesterday, of today.
And i would like to get ready for tomorrow.
The forecast is, let's say 21 degrees max.
If your can add a differential term, like the change of max temp from yesterday, i can know right away what sold I wear.
Sometimes it's enough to know the today gonna be the same as the day before. Or 2 deg lower (i.e. take a sweater...). Etc.
Thanks.