First, it's not Disney that has the ban in place, it's the department of Agriculture. It seems that they have an FDI (Fire Danger Index) that guides their decisions.
http://www.freshfromflorida.com/Div...Service/Wildland-Fire/Current-Fire-Conditions
While I don't know if it's a hard and fast rule, I suspect it's more of a guideline and that there is a "Board" who makes the determination probably by a consensus.
Probably a very similar thing in California as well.
From the website listed above:
Summary and Fire Potential Outlook
Florida is forecast to become drier and warmer this spring. February is when we typically see severe weather roll through the state, however, aside from the line that came through northern Florida in January, there hasn’t been much significant rainfall at all. Much of the state is in a rainfall deficit, and it’s expected to stay that way until the rainy season begins in the summer. Predictive Services with the National Interagency Fire Center in Boise are forecasting that in April, regions of Florida east of the Suwannee River will have an above normal Significant Wildland Fire Potential. This will expand to include the whole state in May and June.
The next seasonal outlook will be the first week in July, 2017.
I suspect you won't see much change before that July 2017 Seasonal Outlook.