RiverRider
That's a valid concern, and I can't speak for all chronographs. Oehler chronographs all use a crystal oscillator for which the temperature effects are less than the temperature effects on the length of a stainless steel tape or ruler. In other words, don't worry. The effect is there, but is insignificant. The "freeze up" at approximately 0F noted by Mule Deer is usually caused by the battery failing. One writer keeps his chronograph happy at subzero temps by letting it share his handwarmer.
