I have a cateye velo 8 on my commuting bike. It just works in all kinds of temperature/weather. My touring bike has a 10 year old cateye mity and it has never given me problems either.

I used to have a wireless computer that kept going out when the temps were below 5C (40F). Not consistently either. Some days it would record 15km out of 20, some only 5km. That was my first (and last) wireless computer.