I've had a few of those days, oddly enough i had one this summer. This year though i spent some money and got decent rain wear and i am sooo happy i did, fall and early winter is rain season in boise (luckily being in a valley means we get rain and not much snow) and i think its rained like 9 days since oct 1 and ive so far stayed dry with exception of my feet i still havent figured that one out, i just do the same as you and keep shoes and socks at work. And +1 on water tight panniers by far the best thing EVER invented!!!