I've been caught in SoCal storms as late as early May that reveal my gear to be inadequate. The gear most thru hikers carry wont be enough to be safe, let alone comfortable, should the weather turn. So, it is imperitive to be aware of the weather forecast. If you see a hot streak coming get high. If you see a rain storm coming get low. At a certain point of either extreme know when to get off the trail.

There are various places along the trail where cell reception is adequate enough that you can check the weather. At the very least check in town.

Right now I'm watching it snow in Julian. Yesterday my tent was almost destroyed by wind gusts. I'm glad I check the weather on my way down from Mt. Laguna. I'll head into the San Felipe hills tomorrow after the wind dies down. It should be nice and cool sans 50 mph winds. The San Felipe hills can be hell. I dont envy the herd that passes through a month from now.