My commute was 25 miles each way, 1400 feet (426m) of ascent each way, with no transit option. Last winter, a surprise blizzard rolled in during the week. My ride home took me 2.5 hours, rather than my usual 1:40, but I managed to stay upright the whole ride despite riding on slicks. Fixies and foul weather, better together!
Salt, ice, and unsealed bottom bracket: creaking every 2-3 weeks!
Cartridge bottom brackets FTW. Shimano no longer makes the UN-54/UN-55, but that was my goto for a very long time. Costs about $16USD and lasts forever. One of my bikes had over 100000 miles/160000km on a single UN-54. That bike saw it all: flooding (immersion), salt, ice, rain, neglect, and “Star Wars Ep 1.” It was still smooth and solid when I sold that bike.