Last year was extremely dry over the entire area that the PCT covers. Here where I live in Oregon, there was measurable precipitation on only two days between July 1 and October 10. Almost everyone who's ever thru-hiked the PCT northbound has had to hike in significant stretches of snow in California's High Sierra, but last year, no one did. I ran into one of the earliest NOBO thru-hikers last year and he said that the biggest patch of snow he had to cross in California was a hundred yards or so on the approach to Forester Pass, the PCT's high point at 13,153ft. Later thru-hikers last year, like my friend Spins, literally did not have to hike over snow once in the Sierra, which must be unfathomable to the people who have done it in high snow years and spent days without setting foot on solid ground.
Is it easier to thru-hike the PCT in a low snow year? I guess I don't really know, having not thru-hiked it in any type of year. I admit that the thing that instinctively scares me most about the PCT is traversing the Sierra in snow. From everything I've read, the mental and physical effort expended is incredible: the trail is invisible, requiring you to have strong map-reading and navigation skills (which I don't); stream crossings are flooded with snowmelt every afternoon; mosquitoes are breeding in impossible quantities on the melting snow; and postholing for miles on end is a massive undertaking that slows your pace, increases your calorie consumption, and drives you insane.
So let's say it's another dry year, and I get off easy and don't have to hike on snow very much or at all in the Sierra. Unfortunately, the tradeoff is the potentially more life-threatening problem of waterlessness. This doesn't instinctively intimidate me the way the prospect of a snowy Sierra does—but it should. In wet years on the PCT, such as 2011, I've heard that there are enough seasonal water sources flowing in the desert that one rarely has to walk more than 10 miles without seeing a source—it's almost like the AT. On the other end of the spectrum, I've read Scott Williamson mention packing 15 liters of water for a 65-mile stretch without reliable water sources in SoCal in 1992, which was a drought year. That's 33 pounds of water (1L=1kg=2.2lb). These days, volunteers leave water caches for thru-hikers in the desert, but those don't count as "reliable sources," as they can't be restocked as often as hikers drink them up. Nobody wants to show up empty to a water cache, and find that it's empty too. I'm a pretty heavy drinker (of water), so I bet I will be staring at situations in the desert, and possibly NorCal and Oregon, where I need to pack 8 liters of water or more.
Wildfires are also an issue in drought years, although as far as I know they don't threaten the physical survival of thru-hikers the way that dehydration does. What they do do is mess up hiking schedules and routes. By mid-August last year, 13 separate sections of the PCT were closed due to wildfire, which meant that there was an official re-route for every one of those places, and most of the time, the re-route was walking down a road, which is a lot shittier than walking through the woods. Hikers converge on towns waiting out fires, which honestly sounds miserable to me. I would have too much energy and too little patience with crowds of people to make that a happy situation.
Basically, I have to keep reminding myself that even though it appears I'm facing a dry, low-snow year, this doesn't mean that I'm getting an easier trail experience overall. Looong waterless stretches are tough, and wildfires are tough, and I have to be mentally ready to confront those challenges the same way I'd be ready to face deep snow and bad early-season weather.