My Garmin Edge 500 display is good to at least 12 °F - the lowest temperature I've used it thus far this winter. I have noted that the temperature reading becomes inaccurate below maybe 20 °F - it reads consistently high by a few degrees as compared to nearby weather stations at the same time (checked after the ride). I have a theory that this is a small amount of waste heat coming from the unit, but I"m not sure (It's not the sun - the effect is also observed at night). But the unit is rated down to 5 °F, if I recall correctly, and the display is fine when cold.