Female blue belly lizard. Female lacks two enlarged scales on the cloaca an has little to no blue on the neck. Both males and females have blue bellies. Male has black line along inner margins of the blue belly. Both sexes can have yellow thighs though the males usually have more. Males get darker with each shed growing up to the point where the belly can be mostly black. Females keep the white bellies with speckles of black.
For visual reference, here's a shot of the underside of a Male Sceloporus occidentalis: (photo credit @ joesjoes20) https://static.inaturalist.org/photos/333472236/original.jpg

Coast Range Fence Lizard (Sceloporus occidentalis ssp. bocourtii) A.k.a. Blue-belly lizard. They are in the Spiny Lizards (Sceloporus) genus and measure 2.25 - 3.5 inches long from snout to vent (5.7 - 8.9 cm). Color is brown, gray, or black with blotches. Sometimes light markings on the sides of the back form stripes or irregular lines, and sometimes dark blotching may form irregular bands. The rear of the limbs is yellow or orange. The base color of the throat and underside are typically pale to dark gray and sometimes black. Males have blue markings on the sides of the belly edged in black, a blue patch on the throat, enlarged postanals, enlarged femoral pores, and a swollen tail base. On some males the throat and dorsal coloring around the bright blue can be very dark. Some scales on a male's back and tail become blue or greenish when he is in the light phase. Females have faint or absent blue markings on the belly, no blue or green color on the upper surfaces, and dark bars or crescents on the back. Juveniles have little or no blue on the throat and faint blue belly markings or none at all.
Western Fence Lizard is diurnal (active during the day). It is often seen basking in the sun on rocks, downed logs, trees, fences, and walls. It prefers open sunny areas. It is active when temperatures are warm, becomes inactive during periods of extreme heat or cold, when they shelter in crevices and burrows, or under rocks, boards, tree bark, etc. It is common and easily encountered in the right habitat. This is probably the species of lizard most often seen in the state due to its abundance in and near populated areas and its conspicuous behavior. Males establish and defend a territory containing elevated perches where they can observe mates and potential rival males. Males defend their territory and try to attract females with head-bobbing and a push-up display that exposes the blue throat and ventral colors. Territories are ultimately defended by physical combat with other males. Tail can break off easily, but it will grow back. The detached tail wriggles on the ground which can distract a predator from the body of the lizard allowing it time to escape. It eats small, mostly terrestrial, invertebrates such as crickets, spiders, ticks, and scorpions, and occasionally eats small lizards including its own species.

A Guide to the Amphibians and Reptiles of California (with subspecies range map): http://www.californiaherps.com/lizards/pages/s.o.bocourtii.html

HerpMapper https://www.herpmapper.org/taxon/Sceloporus_occidentalis

Fun fact about Sceloporus occidentalis ssp. bocourtii:
"In California, western black-legged ticks (deer ticks) are the primary carriers of Lyme disease. Very tiny nymphal deer ticks are more likely to carry the disease than adults. A protein in the blood of Western Fence Lizards kills the bacterium in these nymphal ticks when they attach themselves to a lizard and ingest the lizard's blood. This could explain why Lyme disease is less common in California than it is in some areas such as the Northeastern states, where it is epidemic."
http://www.californiaherps.com/lizards/pages/s.o.bocourtii.html

And for more technical information:
"Diagnosis (bocourtii): This subspecies can be distinguished from members of the biseriatus exerge by its smaller size, and from all other subspecies by the virtual absence of blue gular semeions. Gular scales which are at least 50% blue averaged 1.4 (0-16, N = 84) in adult females and 7.4 (0-45, N = 101) in adult males. Of the females examined, 66 (78.5%) had no blue gular scales. Adult males examined generally had fewer than 20 such scales, and in 43 (42.5%) blue gular scales were absent (Bell, 1954b). The chest, chin, and IASA are light-colored, often white (Bell & Price 1996)."
The Reptile Database https: https://reptile-database.reptarium.cz/species?genus=Sceloporus&species=occidentalis