after doing this bike commuting thing in chicago for nearly a decade now, i follow the weather almost obsessively.

everyone likes to make fun of weather forecasting, and 30 years ago it often was a "best guess", but with 21st century science and computing power being what it is, day-of forecasts have gotten profoundly accurate, at least here in chicago from my experiences.

7 days out? yeah, that's still mostly a crap shoot, but for what will likely happen later this afternoon? they've gotten pretty damn good. and it's always percentages, so i play the odds. if i wake up on january morning and i know the streets are bone dry, but the forecast says there's a 30% chance of snow/sleet/freezing rain etc. for the afternoon, then i'll ride the studded tire winter bike as a precaution. if the forecast is for things to stay dry all day, then i'll ride my regular commuter.

it's a system that has worked profoundly well for me for many year, and it means that i have to ride on studs much less often than if i only had one commuting bike. YMMV.