In the Monterey bay area, I can pick up at least two in the 406 to 420 range. They are using them as a link from the NWS office to the transmitters and using directional antennas, so the signal isn't very strong unless you are close to the path.
What you'd need to do in your area is set up your radio to scan that range, and make sure you have a good UHF antenna. Ideally you'd want to be in the path, or close to it, between the local NWS office and the VHF transmitter. While this is not intended as a UHF version of the standard NWS VHF broadcasts, it can work in a pinch. I certainly would not rely on it since coverage will be poor, and there isn't much keeping the NWS from changing their feeds to another means, microwave, wireline, etc.