High season is April–October (with an early blip in March on the South Rim  during spring break). For the North Rim , high season doesn’t begin until mid-May, and summer is the only season, unless a snowy 50-mile trek sounds like fun.
Winter is also an especially good time for watching wildlife. Deer and elk wander close to Grand Canyon Village , and ponderosa pines shelter juncos, nuthatches, and chickadees. Keep in mind that the higher North Rim can be inaccessible in winter months.
Autumn is a glorious time to visit Grand Canyon. Summer crowds have eased, and summer temperatures lose their grip on the South Rim and inner canyon. Warm, sunny afternoons and clear nights bring ideal hiking weather. On the North Rim, aspens begin to turn gold in September, peaking the first week of October. Summer lingers longer on the South Rim—fall doesn’t arrive with a burst of color but with a musical crescendo as the annual Grand Canyon Music Festival  begins. If you’re a birder, bring your binoculars, because September and October are great months to watch migrating raptors use the canyon as a flyway.
Spring is a little chancier—snow can blanket North Rim locations into May, and spring snowstorms aren’t uncommon on either rim. Wildflowers begin blooming in the inner canyon deserts, moving up to the South Rim by April, adding splashes of red, yellow, and purple along rocky rim overlooks. Temperatures are usually comfortable, though the rim can be windy, especially in March.
Summer at Grand Canyon requires coping strategies. Though mornings and evenings on both rims are relatively cool, the midday sun bakes trails and overlooks, and the inner canyon becomes a shadeless furnace. Time hikes for early or late in the day, choose trails with afternoon shade, and pack plenty of water. Or head for the higher environs of the North Rim, where purple lupine lingers under a canopy of aspen and spruce, and mule deer graze in mountain meadows.
Be ready for anything. Even on the South Rim, it can snow in June, and it isn’t uncommon for temperatures to hit 90°F in October. Canyon roads, trails, and buildings may close temporarily for needed maintenance. Your cell phone may not get a signal, and the train could be late. But the afternoon thunderstorm that spoils your hike to Indian Garden  might yield a rainbow during a sunset viewed from Yaki Point .
No matter what season you visit, you’ll want to bring an easy-to-carry water bottle and moisturizers for your skin and lips as well as protection from wind and sun. Weather conditions can change quickly. Layering is the best strategy to help you shift from chilly mornings to sunny afternoons. Pack for your activities: broken-in boots for a hike, a small flashlight for camping or for walking around Grand Canyon Village at night, a waterproof jacket if you’re visiting during the summer monsoon.
What you won’t need at Grand Canyon is a tie or dressy heels. As long as you lose the backpack and put on a pair of clean jeans and a nice shirt, you’ll pass—even at El Tovar, the canyon’s swankiest restaurant.
Visitors to the Grand Canyon most often fly into Phoenix or Las Vegas and then travel overland via bus, train, or car. Accommodations outside the canyon can be found in the gateway cities of Flagstaff, Williams, and Page. Reservations are a must. River trips  and mule tours  often fill up six months to a year in advance, and backpacking permits require careful trip planning and applications up to four months before the month of your trip. Accommodations on the South Rim often sell out during high season. North Rim rooms are especially hard to get during autumn, when aspens turn gold and leaf-peepers head for higher elevations.
If you travel the Grand Canyon area by car, gas up whenever you get the chance, especially if you plan on exploring roads in the national forest or reservation lands surrounding the park, where distances are great and service stations few. Even on the South Rim, there’s only one gas station inside park boundaries, and it’s 25 miles from Grand Canyon Village . And always, always keep water in the car.
To make the most of your time, do your research in advance. The National Park Service website (www.nps.gov/grca ) includes helpful tools for planning a trip, including permit applications, trail closures, backpacking advice, and weather forecasts.