By the same token, where they are recording could be dryer than the surrounding areas
The maps and classifications aren't just current soil moisture and rainfall. It's not a statistical model but an interpretation. Thought this from the Drought Monitor web was interesting. Weather (rainfall and temperature) play a big part, obviously, but a lot of other data and observation go into the mapping.
How do we know when we're in a drought?
When you think about drought, you probably think about water—or the lack of it. Precipitation plays a major role in the creation of the Drought Monitor, but the map’s authors consider many data sources. Some of the numeric inputs include precipitation, streamflow, reservoir levels, temperature and evaporative demand, soil moisture and vegetation health. No single piece of evidence tells the full story, and neither do strictly physical indicators. That’s why the USDM isn’t a statistical model; it’s a blend of these physical indicators with drought impacts, field observations and local insight from a network of more than 450 experts. Using many different types of data and reconciling them with expert interpretation is what makes the USDM unique. We call it a convergence of evidence approach.
A detailed explanation of the U.S. Drought Monitor.
droughtmonitor.unl.edu