A gas stove may be required for cooking. In country new to you, a topographic map and the ability to read it are vital. A compass should also be included in your gear. There are many excellent books available on both map reading and compass use. The USDA Forest Service Pacific Northwest Region puts out an excellent document, Recreation Aid No. 2, 'Map and Compass.
Storms come up quickly in the mountains.
Snow or cold rain can be expected any time of the year even though the sky may have been blue and clear when you started out. The bottom line is to be prepared and have a plan. It is important to always carry a good knife, a flashlight, and fire starting material whether you are out for one day or many. Always be prepared for cold, wet weather. On pack trips an ax, a shovel, and a water container are useful and may be required in some areas.