it's not legal to leave your pet in a hot or cold car.
Inclement weather, cold or hot, can literally be a killer for a pet left in a car. Did you know that on warm days, the inside of a car heats up very quickly? When its 85 degrees outside, the temperatures inside a car, even with the windows left slightly open, can reach to 102 degrees in 10 minutes, and reach 120 degrees in just half an hour! Even leaving your pet in the car for just a few minutes in extreme heat can result in its death. On freezing cold days, your vehicle can be an ice box causing hypothermia and death.
597.7 (a) of the California Penal Code "Animals in Unattended Motor Vehicles" states:
No person shall leave or confine an animal in any unattended motor vehicle under conditions that endanger the health or well being of an animal due to heat, cold, lack of adequate ventilation, or lack of food or water, or other circumstances that could reasonably be expected to cause suffering, disability, or death to the animal.
A first offense is a $100 fine, subsequent violations are $500.
Please, if you don't have to take your pet with you, leave them at home.