The weeds that you see in this photo (click on it to see it larger) are cool-season broadleafed (non-grassy) weeds. They germinate in the fall, establish their roots over the winter, then flourish and bloom in the spring. Clockwise from upper-left, they are dandelions, chickweed, henbit and clover. These are photos taken in February. Look for smaller versions in your lawn now (probably without flowers).
You could have prevented these with an application of Gallery pre-emergent weedkiller in early September, but now it's too late for this generation of the weeds. You need to apply a broadleafed weedkiller spray to them sometime in the next week or so, especially in the northern half of the state. These products contain 2,4-D, and they may contain two other herbicides. The labels for many of the products say that temperatures must be 70 degrees or warmer in the daytime, and that no rainfall or irrigation should fall on the treated area for at least 48 hours. There are products that will work at somewhat cooler temperatures, and your local independent nursery professional will be able to show them to you.
My preference is products that contain only 2,4-D, since it is not active through the soil and roots. That way, I have much less concern about the well-being of trees and shrubs that may share the same soil. In any event, I apply the herbicide very carefully only to the weeds' leaves. I prefer to use a dedicated tank sprayer that will allow me to coat the leaves with the fine spray. Again, less active ingredient put into the environment.
Once you get into the middle of the winter (January and early February), these weeds will begin to burst into full growth and bloom, and temperatures will still be too cool to spray. Take care of them during warm spells over the next several days.