Try not to get too nervous! While it’s unusual for a driving test to be canceled because of rain, it is possible that your test will be canceled if the storm is severe. It’s much more common for driving tests to be postponed due to snow or ice, though, because of the danger associated with slippery conditions.
If you’re really anxious about taking your test in the rain, you can reschedule it for the next available appointment on a forecasted clear day. To do this, you’ll need to call or visit the DMV where you were planning to take your exam. They’ll probably ask you for a few personal details, like your name, license or permit number, and possibly your Social Security number—so have that information ready to go.