Similar to Vivi - laziness usually wins. It's been a long time since I've had to scrape my car or shovel snow, but I can imagine that if I had plans to go anywhere other than work I'd probably cancel them.

If snow and/or rain could possibly make my journey take twice as long as it normally would, I'm not going to make it. Not because I'm afraid of driving in poor conditions but because my plans most likely are not worth the time it would take to reach them.