Many plastic snowdomes, and some glass ones, are filled with plain water, and are subject to freezing/expanding/cracking in cold temperatures. However, we have found that snowdomes will arrive in good condition by shipping domes via 2-day air during even the chilliest times. Costs extra, but absolutely worth it. It is very important that your faithful delivery person not leave your snowdome package outside, awaiting your arrival home. This is how the term "domesicle" was invented. You may want deliveries sent to your office instead, where everyone can admire your excellent taste in snowdomes. Some glass snowdomes are filled with an anti-freezing additive during manufacture, which helps reduce the freezing problem.