It’s likely your water meter. If you have a wrench, an extension cord and a small portable heater or hair dryer, open your water meter cover in the sidewalk, and drop the heater in there for a while (make sure there is no water in the meter hole.) the meters freeze BEFORE the pipes in your house almost every time because they aren’t insulated and the pipes in your house are. If you have some fiberglass insulation, wrap your meter with it after thawing it. This can prevent it from happening again.