Maybe it's climate change; maybe random chance. Whatever the reason, Pennsylvania's deer season in recent years has offered it all -- daylong downpours, short-sleeve heat, tree-toppling wind and, this year, perhaps snow and cold.

What never changes, though, is that if you want to get a deer, you've got to stay out. And if you want to stay out through fickle conditions, you need to be prepared.

You could throw everything you might need into the vehicle and head for the woods. But every time you walk back to the truck to retrieve a raincoat, or to shed a parka in the heat, a nice buck might amble past your stand.

The answer, according to hard-hunting experts, is to use a good backpack, designed with a hunter's needs in mind.

"Anytime you go into the woods, you want to be prepared for the expected and the unexpected. A backpack does that for you," said Brian Thompson, general manager of Woodlands World outdoor store in Uniontown. "I'm ready if I need to stay out all night, and it's even served me as a shooting rest. When I was a kid I stuffed a sandwich in my pocket and went, but I now consider a good pack to be essential."

Bolstering Thompson's credentials in outdoor retailing are past hunts for caribou, elk, bear and deer in far flung places like Quebec, New Brunswick, New Mexico, Texas and Colorado, as well as West Virginia and Western Pennsylvania. Thompson's customers get hard-tested advice.

Even without the occasional overnight emergency, Thompson says a backpack makes him a versatile hunter, able to adapt to changing conditions.

"I can stuff in a raincoat in case it rains, and a fleece vest if it gets colder and I've got room to stash my heavy coat if the weather gets warm. My pack is like a temporary base camp on my back."

Selecting a backpack is not complicated. In fact, the prime consideration is the same as when buying a couch from which to watch Steelers games.

"Comfort is the key. A lot of people are drawn to bells and whistles, but the point is making a hunt versatile and comfortable," said Dominick Murphy, sales manager for Badlands Backpacks of Salt Lake City, Utah. "Regardless of who makes the product, the bottom line is how the pack interfaces with the body. Try on different styles in the store before you buy."

In-store try-ons, though, won't tell you much unless you simulate hunting situations.

"Go right over to the reloading counter and put some shot in that pack and weigh it down," Murphy said. "Whether you're packing out elk quarters or just lugging a jug of coffee all day, you won't know how it feels unless you put some weight in there."

Murphy and Thompson agree that design features, such as the suspension system, hip belts, and the distribution of weight over the body are what make a pack both comfortable and durable. Both agree, too, that you don't have to take out a second mortgage to get a dependable pack, but you shouldn't buy junk.

"Buying cheap stuff is not worth it when you hunt hard," Thompson said. "You can get a good pack from one of our quality manufacturers like Badlands, Hide Away, Scent Blocker, Rocky or Trail Tech for between $75 and $125."

Beyond comfort, Murphy said what's important to him is accessibility.

"I like to know where all my stuff is and be able to get to it without sorting through everything else," he said. "We try to design accessibility and organization into our packs. You shouldn't need to go through your raingear to find your flashlight."

Packing a backpack is, to some degree, a matter of personal preference. Over time, a hunter comes to know what's essential and what makes the day more enjoyable. Typical items carried by experienced packers include a dragging rope, knife, whistle, lunch, water, compass or GPS, maps, rag for cleaning hands after field dressing, First Aid kit, fire building materials, emergency blanket, extra clothes, hand warmers and cord for attaching that deer tag.

"Before I go on a trip I make a list of what I'll pack," Thompson said. "When I get back I check off the things I didn't use, and the things that I did. Then I know what to pack next time."