In cold temperatures, Transitions Lenses will get darker. At very high temperatures, Transitions Lenses will not be as dark due to the thermal process affecting the molecules. This is a normal reaction for photochromic lenses.
Experts recommend that wearers exposed to extreme conditions (beach, watersports, skiing...) consider a second pair of polarized prescription sunglasses.
Gauging the effects of temperature:
The darkness of the lens is dependent on the number of photochromic molecules open at any given time. In hotter temperatures-- think of a pot of boiling water—the molecules have more energy and are closing at a faster rate. Therefore, although the amount of light energy (sunlight) present is the same, the number of open molecules on a hot day is less than the number of open molecules on a very cold day. This is why a photochromic lens is darkest in cold temperatures and returns to clear quicker in warmer temperatures.
Transitions lenses are the number one recommended photochromic lens worldwide. Our scientists are always challenging themselves to improve our photochromic technology and create products with improved temperature independency. In fact, the latest Transitions lenses become 10 percent darker in hot temperatures than the previous generation.