Their name is for a reason, they live in burrows in the ground, typically sharing burrows with squirrels that dug out the burrows, they are about the same size as the squirrels as well and are pretty active during daylight. Their habitat in Orange County has been cut drastically. At Bolsa Chica Wetlands, there used to be a colony of them until the new housing development paved right over their burrows on the highlands of the wetlands. Occasionally, 1 or 2 are spotted in the area so it's possible a few remain. They are also occasionally seen at Newport Back Bay as well as Seal Beach Naval Weapons Station but access is limited to occasional visiting times for the public. Another location they call home for now is Banning Ranch in Costa Mesa which is completely off limits to the public, plans for development are in the works which could of course have devastating impacts if approved.
Great areas to find burrowing owls outside Orange County are Chino and Salton Sea in the farming area around the Southeast of the lake.