Zion National Park ranges in elevation from just under 4,000′ to over 8,700′, and temperatures can be quite different at varying elevations. Zion Ponderosa sits at 6,500′ and is therefore cooler than the bottom of the park, and that is a great thing during hot summer months. The upper areas of the park are part of large plateaus and are less shielded from breezes so during winter, spring, and fall, wind-chill is something to take into consideration.
Layered Clothing: With exposure to wind, sun, and the rare chance of rain or snow, it is always good to bring along some layers of clothing that can be easily added or removed. Light long sleeve shirts, and zippered leg-pants that turn long pants into shorts, or vice-versa, can be handy. If you intend to be in the water (slot canyons) it is wise to put some articles of clothing in water-proof or zip-lock bags so you’ll have some dry clothing.
Rain / Wind Protection: It is wise to include an inexpensive rain poncho, and an emergency reflective foil blanket, as these items are small, light, and always easy to include in a small backpack or waist pack. These items can be converted into a crude shelter if needed.
Broad Brimmed Hat: No matter the time of year a hat is always a good item to have along since the skies over Zion are mostly clear, and sun exposure should be anticipated. It’s always wise to include sunscreen for any other parts of your body that will get too much sun exposure.
Water: No matter the time of year, if you are outdoors and walking for any lengthy period of time, you’ll need water. In summer months it is wise to plan on approximately ½ a liter of water for each hour, and depending on your level of exertion you may wish to have more. Water filtration bottles are easy to carry and not a bad idea for emergency situations.
Insulation: If you intend to go into one of the Zion area slot canyons where you’ll be in and out of water, then you’ll want to make sure you’re prepared for water temperatures and sun-shaded canyons. In non-summer months water and air temperatures can be quite cool and you’ll need insulation for your feet, and/or your whole body (wet or dry-suit).
Other items for emergencies: It’s always good to bring a portable first aid kit and some matches or some way to start a fire to keep warm.