As I write this blog, there are more than seventeen wildfires in California. Many have the potential to bring smoke to the John Muir Trail, but the four listed above are the most significant.
The Ferguson Fire is by far the most serious; it is only 30% contained. More information regarding the fire can be found here.
The Lions Fire is 92% contained. More information regarding the fire can be found here.
The Georges Fire is more than 70% contained. This fire closed Whitney Portal for several days in the beginning of July. More information regarding this fire can be found here.
The Horse Creek Fire is a small one that is already nearly 100% contained. More information regarding this fire can be found here.
For more information on fires throughout California you can consult the California Statewide Fire Map.
Note that on the illustration, above, I have indicate the prevailing winds in the area for July, August and September. Winds are generally out of the northwest during the afternoons and evenings. For a few hours each morning it is normal for them to shift from the south. These are prevailing winds, though, which does not take into account daily weather patterns. Winds on any particular day could come from any direction.
One last note: the Carr Fire is much further north, but is so large that is could foul the air above the northern half of the JMT. More on the Carr Fire here.
Good hiking, Ray