Come anytime of year! You'll always find regions with a pleasant climate. Grand Canyon National Park and most other major attractions stay open year-round. The seasons do have a big influence on the Great Outdoors, however, so it's worth planning your travels to take the best advantage of the state's attractions.
In the high country of the north and east, this is a wonderful time to enjoy pine-scented breezes on a hike, out on the water, or on a scenic drive. Mountain towns put on many festivals, concerts, and rodeos.
The deserts turn into an oven, so you probably won't linger in them, but air-conditioning makes life pleasant even here, and you may wish to take in some of the top sights in cities such as Phoenix and Tucson. If you'd like to stretch your legs, early mornings can be pleasant for short excursions into the desert. At the Grand Canyon, the Inner Gorge becomes too hot for hiking, but the upper and rim trails offer fine scenery and the likelihood of a cool breeze, especially on the North Rim. Irregular thunderstorms arrive in late summer, adding refreshing coolness to the air at the higher elevations and miserable humidity to the desert. Plants sprout new greenery and some burst into flower.
Nearly the entire state enjoys warm and dry weather, though hot temperatures can linger into October at the lowest elevations, and the possibility of snow gradually increases on the plateaus and mountains. Aspens turn to gold in the high country in late September and early October, followed by colorful displays of oaks, cottonwoods, and other deciduous plants in canyons lower down.
Desert dwellers enjoy springlike weather for most of this season. It's also a fine time for exploring the rugged mountain ranges of the south and west, where you're likely to come across ghost towns, prehistoric rock art, and other reminders of the past. Flocks of "snowbirds," mostly retirees, leave their frosty northern homes for the sun in Arizona's luxurious resorts or out in remote desert locales. Phoenix, Tucson, and the other valley communities put on many events during the cooler months.
You can also enjoy travels in the high country, as weather tends to be bright and sunny even in midwinter. Keep an ear out for weather forecasts, because passing snowstorms can make driving difficult for a few days. Only a handful of highways close for the entire winter, most notably AZ 67 to Bright Angel Point on the Grand Canyon's North Rim. Gentle rains—snow in the mountains—arrive now and then.
The warmth and flowers arrive as early as February in the low deserts and gradually work their way up to the higher mountains by May. The desert country shines with wildflowers in early spring, the choice time to visit. Each year's floral display depends on both the amount and timing of rains in the preceding winter. By April, when the saguaro and other large cacti bloom, the snowbirds have long gone and locals start up their air conditioners. The mountains shake off most of their remaining snow and experience warm, dry days.
Comfortable walking shoes should be at the top of your list—Arizona has many wonderful day hikes and strolls! Also check that you have a hat and sunscreen.
Arizonans tend to dress informally. You're unlikely to need a tie or an evening gown, and "business casual" will do fine at most upscale restaurants. A warm jacket or sweater will often be handy in the evenings, as the dry air quickly cools after sundown. Winter gear will keep you comfortable on travels in the high country, when temperatures can drop well below freezing.
On to The Regions