Knowing your hardiness zone is so important to the health of your succulents! It helps you to know not only what plants can tolerate your seasons, but also the growing cycles.
If you're in the US, this map by the USDA will help you find your growing zone. You can even enter your zip code and get a more detailed description, or search by state.
For readers outside of the US, this Plant Hardiness Map can help you determine your location's zone.
Each succulent is rated for a specific minimum temperature. While it won't help you find the best heat tolerant succulents, knowing your growing zone will help you determine how to care for your succulents over the winter.
Once you understand what plants can thrive in your climate, it's also important to understand succulent dormancy. This will help you know what will grow best during your cooler and warmer seasons.