In addition to written fire regulations, which are occasionally vague as to their meaning and interpretation, there is also extended to the district rangers and to the park chiefs, authority to fashion ad hoc measures on a daily basis to protect lands in their jurisdiction from reasonably apparent risks. Late in the season here in California, especially in dry years, it is not uncommon to meet with a total prohibition on fires including the striking of a mere match. In ordinary years fires are prohibited above a certain elevation, I think 10,000 or 10,500 in those parks and wilderness areas through which the JMT runs. (I am sure other Cal hikers can contribute here on the specific elevation).
As a practical matter, I have been hiking when fires were not precluded in the area where I was camped and I would not risk a fire because of wind or dry conditions or both which in my own judgment made a fire too risky or down right careless. These conditions already exist in many areas in the Sierras, in my opinion, and it is not even June yet. I have been up there twice in the last month and startled as to the conditions. I have never seen it this dry this early in my 30 years of hiking in the Sierras.
The grass should be green, the meadows muddy and marshy and every depression filled or flowing with run-off. In April on a hike from Kennedy Meadows to Monache Meadows, there was no water between the Kern and Monache. Furthermore Craig Creek, an intermittent running usually in the spring was bone dry, except for about 50 yards, and Clover Meadow was hardpan and the grass dry burnt yellow as it was in Monache. Last weekend I found Southfork Meadows below Cottonwood Basin to be the same. Southfork Creek was running low and relatively warm. The dry grass in the meadow made excellent fire tinder for my Bushbuddy. In fact the use of the BB was risky in my opinion due to the conditions. Some of the streamlets that allow for good camps in perimeter areas below the basin were just not there.
The point is that it is already so dry in the Sierras that the condition for forest fires exist now. We have already had significant fires here in Southern California. I can't imagine what it will be like up there in August and September. It is possible to have sufficient rain in the summer to assuage these conditions, but this type of regular precip in the summer is the exception rather than the rule. I am just hoping that by August when I hike the JMT that I will be able to see the blue sky through all the smoke. Unless we see unseasonable rain fall this summer, I believe that conditions will be so dry that not only wood burning stoves such as the BB will be prohibited, but there is a possibility that any kind of open flame will be precluded along the JMT.
Hopefully I am wrong about all of this and I suffering from the latent affects of the early manifestations of alarmism. Possibly other California hikers have a different view. If so, please comfort me with your observations to the contrary. Maybe, just maybe, the Good Lord will bless us with an abundance of rainfall, out of season, this summer.