I am 25 miles south of Atlanta. I mulch my beds with wheat straw or pine straw or shredded leaves all through out the year. All 4 seasons. I am also doing square foot gardening mostly since 2011. In the summer you need the mulch to keep in the moisture. In the fall and winter you need the mulch to help insulate any veggies growing and also to keep the rains from washing out the nutrients.

For the cold season, you want to mulch to keep the soil warm which keeps the roots warm. The mulch will break down over time into organic matters and feed the soil.

Woodchips mulching is a good idea since it promote more fungal activities when broken down, but not the the colored ones from the hardware stores, you want natural untreated woods that will breakdown over time. You just have to not mix the woodchips into the soil which can tie up the nitrogen while it's broken down, but afterward they release more nitrogen.

Otherwise you can use leaves which breaks down faster.

If you really want you can create a hoop house for your plants to preserve the temperature.