The U.S. Department of Agriculture's Forest Service offers detailed maps on current and past wildfires. The Map Archive on the website (fs.fed.us) allows you to view all past wildfire activity.
The Forest Service's Fire Detection Maps use satellite information to provide up-to-date information about wildfire activity across the United States. The maps are subdivided by region into several sections of the United States.
A more interactive tool that allows you to view wildfire and other environmental activity is available at earth.nullschool.net. This open source project allows you to view real-time overlays of wind, sea current, carbon monoxide concentration, and dust particulate projection in an interactive 3-D model of the world.