There is no better article of clothing to wear rock climbing on warm summer days than a pair of shorts. It's best to buy and wear shorts that are specifically made for climbing since they're made of durable fabrics, have reinforced seams, and are designed for comfort and ease of movement. Oh, and you'll look good in them too!
Wear Your Shorts Long
Make sure that your shorts are cut long enough so that the leg loops of your harness don't rub against bare skin. While you may like the short shorts look, the shorties just don't work well for climbing since they tend to bunch up above the leg loops. Wear shorts that come to just above your knees and extend at least four inches below the harness leg loops. Most climbing-specific shorts are long enough. Otherwise look for a pair of skateboard shorts.
Loose-Fitting Shorts are Ideal
You also want your shorts to be loose-fitting. Tight shorts, unless they are made with lycra or some other stretchy fabric, restrict your leg and hip movements when you're climbing. When you're climbing, you are constantly extending your legs-stepping high on footholds and stemming out to the side. You want your climbing clothes to move with your body and not restrict movement. Shorts made from stretchy fabrics work better than baggy ones.
Check the Seams Before Buying
When you select shorts for climbing, carefully examine the garment. Look at the waist area and check if there are seams that might create pressure points under your harness. Check out the seams on the inside of the shorts and make sure there are no rough unfinished seams that will chafe on your thighs. Loose-fitting shorts are better than tight-fitting ones, especially for hot summer days when you want airflow.
Gusset in the Crotch is Best
Many climbing shorts have a gusset in the crotch, which allows more comfort and freedom of movement for your legs without the material hitching up, which can be a problem for women. Shorts and pants are usually made with two seams, one front to back and the other from one leg to the other, that intersect in the crotch. A gusset, simply a diamond-shaped patch of material sewn between the shorts legs, takes the place of the crotch seam.
Fabric is Important
The fabric that your climbing shorts are made from is important. Some shorts, like the PrAna Mojo Short, a climber favorite, are made from lightweight poly microfiber fabrics that are quick drying and breathable, while others like the PrAna Zion Shorts are made from an abrasion-resistant stretch nylon fabric and even a cotton twill fabric. There are still climbers who prefer a heavy-duty fabric like that used for the old Chouinard Stand-Up Shorts in the 1970s. Now there is strong abrasion-resistant stretch cotton canvas fabric used in retro shorts like the North Face Cliff Rock Shorts that performs better and lasts longer than the original material. Some fabrics also offer ultraviolet protection by blocking out harmful UV rays in sunny places. If you buy a pair of climbing-specific shorts, check out the fabric. Lightweight shorts that you use for sport climbing simply won't be as durable as heavier shorts that you might use for a full day out on the rocks jamming cracks.
Pockets are Important
Decide if pockets are important to you. Most climbing shorts have at least a zippered back pocket, which is ideal for stashing your car key. Many also have front pockets. I prefer climbing shorts with three pockets, and sometimes even wear cargo shorts with extra exterior pockets-perfect for stashing your phone, tape, pocketknife, an energy bar, or other essentials-on long day climbs.
Wear Knickers for Crack Climbing
Some climbers prefer long pants, even on warm days, partly so that they don't scrape their knees on the rock surface in cracks and chimneys. This is a good idea if you are doing crack climbs, especially on granite, but if you're going sport climbing or toproping, then a good pair of climbing shorts is the ticket. A lot of climbers, myself included, will wear knicker-style pants that extend below knees for crack climbing on warm days. These longer pants, besides keeping your knees from scrapes, are cooler than full-length trousers.
Don't Forget the Sunscreen
When you're rock climbing in summer, you usually won't be wearing lots of clothes. It's important then to remember to use sunscreen to provide essential protection from the sun. Use sunscreen with a sun protection factor (SPF) of at least 30. Apply it liberally on exposed skin, including those bare legs below your shorts, and then reapply later in the day. Sunburn is no joking matter since the effects of sun damage are cumulative and can lead to skin problems later including skin cancer.