Does temperature affect leaf color?

I can tell you in a nutshell that during summer, the leaves of trees are factories producing sugar from carbon dioxide and water by the action of light on chlorophyll. Chlorophyll causes the leaves to appear green. (The leaves of some trees, such as birches and cottonwoods, also contain carotene; these leaves appear brighter green, because carotene absorbs blue-green light.) Water and nutrients

flow from the roots, through the branches, and into the leaves. The sugars produced by photosynthesis flow from the leaves to other parts of the tree, where some of the chemical energy is used for growth and some is stored. During winter, there is not enough light or water for hotosynthesis. While some plants complete their life cycle in one season (Perennials), trees life for many years and survive the cold of the winter. The trees will rest, like a maple tree, and live off the food they stored during the summer until spring comes again. The shortening days and cool nights of autumn trigger changes in the tree. One of these changes is the growth of a corky membrane between the branch and the leaf stem. This membrane interferes with the flow of nutrients into the leaf. Because the nutrient flow is interrupted, the production of chlorophyll in the leaf declines, and the green color of the leaf fades. In other words, short days and falling temperatures signal trees and shrubs to quit producing chlorophyll, which converts sunlight into sugars through the photosynthesis.

Hope this helps :D

I doubt temperature is much of a factor. There are two main reasons for the difference.

1) In all likelihood the tree species are different. In Maryland, you would have a lot of native species of maple and oak, two of the big color-producing fall foliage species in the midwest and northeast. Those same species are not native to southern California. Even if those trees were transplanted in southern California, there would not be sufficient water to maintain those species over a period of years.

2) Even in the midwest and northeast, in years when rainfall is plentiful the deciduous trees are much more colorful than they are after a dry summer and early fall season. As dry as it is in southern California, even if those species had been planted by homeowners, they would be dull in the fall by comparison because of the dry climate.

It's probably because of the temperature difference. I live in California also, so I know it gets pretty warm. When sunlight disappears in fall and winter, chlorophyll (substance in leaves that make the green color) is no longer produce, releasing the other pigments (red, yellow, orange). Because there is more sunlight in California, chlorophyll is still produced while it may not be in Maryland.