I commute quite a distance. I watch a thing they have here called a weather radar and can choose when to set off, so manage to miss most rain.
As to clothing: get proper cycling stuff, as it will be able to bend have a 'cut' so the arms and legs are long enough, legs tight at the bottom so they don't catch in the chain etc.. I wear cycling clothes and carry a spare set for the trip home. It doesn't matter if it rains or not, I need the spare set as I'm always 'going for it' so they are generally soaking with swet anyways. I also carry my work clothers for the day. The whole lot fits in a little rucksack that clips on the seat tube, the rucksack even has it's own natty little rain coat and has two pockets which I have: on one side a pac-a-mac jacket and on the other, a pair of trousers. I keep my work shoes and a selection of ties etc. in my desk at work so I don't need to carry them.
I use NW MTB winter boots as they're 'waterproof', or a pair of SealSkinz socks and a pair of MTB racing shoes (they're full of breather holes, so the water just runs back out of them). These kind of shoes are good as you can clip on, but are still able to walk if necessary, and this make, NW, I use can take spikes on the toes which is good when hitting ice.
When it gets really cold and icy I will wear a full set of body armour as it is quite warm on its own and my commute can get to be pretty dangerous in the worst parts of winter; cars losing control, that kind of thing. Even had a bus mount the cycle path right in front of me last year and send me into a hedge, but I'm wittering now.
Over the top of that have some Race Face gear, really quite tough stuff, last year only the trousers got a small cut and that's from when I slid across some broken glass.
