The sun is as bad as the rain when it comes to your mezuzos. This mezuzah was outside in a clear case. The case became a slow cooking oven and dried the mezuzah to the point where it cracks into fragments as you touch it.
A white waterproof case like the one above is the way to go. It is one peice construction with a plug on the bottom. They are inexpensive and effective. I sell them in sizes 12 cm and 15 cm.