As a starting point for everyday attire, a good rule-of-thumb is to always wear (or keep close):
  • a coat warm enough to spend the next 24 hours outside (including if it rains)
  • shoes good enough to walk home from school / work / wherever

The most "dangerous" seasons in this regard are Spring and Fall, when the days are warm but the nights are cold. For rain protection I don't always have a waterproof coat but have a plastic garbage bag or, more recently, a Wal-Mart disposable poncho (less than $1 USD) in my PSK.

Steve
_________________________
"After I had solaced my mind with the comfortable part of my condition, I
began to look round me, to see what kind of place I was in, and what was
next to be done"