Climbing After It Rains

First, check to see if it’s rained! Avoid sandstone after heavy rains. Instead, climb granite, limestone, and metamorphic rock! These are hard, erosion-resistant, and generally impermeable to water, so rain runs off and the surface dries quickly, even on cloudy days.

Great alternatives to Red Rock after rain are:

Please help us protect our climbing resource!

Before you go rock climbing after it rains, you need to ask yourself some questions to determine if the rock is dry so that you won’t damage or destroy routes and boulder problems.

  • When can you go climbing if it has been raining?

  • How can you tell if the rock surface of sandstone formations is dry enough so climbing will not damage, degrade or destroy routes and boulder problems?

Porous sedimentary rocks like sandstone remain wet after rain.

It’s a judgment call as to when to climb and how deep the moisture has permeated the different types of aztec sandstone we encounter at Red Rocks. Quick but heavy thunderstorms will usually just wet the outer surface layer of sandstone since most of the water runs off the rock. After prolonged rains, however, the rock surface will be wet below the surface, sometimes as much as two or three inches, especially in the softer rock, so it is important to let sandstone dry completely before climbing on it.

Sandstone loses a lot of its strength when wet.

Sandstone and other sedimentary rocks like conglomerate soak up moisture like like a sponge. The water, soaking the rock surface, dissolves cementing agents like clay, silica, and salt between sand grains, allowing the sandstone to lose as much as 75% of its dry strength. Another by-product of wet rock is sand. As the cementing agents dissolve, the individual sand grains are released from the rock matrix. That’s why the surface of sandstone cliffs accumulates sand on handholds and footholds after the rock dries.

6 Guidelines to Assess Wet Rock before Climbing:

If you climb on wet sandstone, you will easily damage the rock surface by breaking off flakes and edges, sometimes completely changing the character and grade of a climbing route or boulder problem. Follow these guidelines to assess wet rock and decide when you can climb without damaging the sandstone.

  • Look at the cliff base and staging area. Look for dark damp areas on the cliff face. Look at flakes and see if moisture is behind them. Look for fresh sand liberated from the sandstone on ledges and holds.

  • Consider the cliff area where you want to climb. What is its location? Does it get lots of sunshine that will dry the rock? Is it in the shade so the rock will stay damp for days? Are trees shading the route and keeping it from completely drying? Does a groove carry water down the cliff onto the route?

  • This usually applies to thunderstorms that drop quick heavy rain on rock that is already hot and dry as in summer. Much of the rainwater usually runs off and soaks into rock at the cliff base or on ledges and shelves. Most cliffs dry in 36 hours with plenty of sunlight. In winter you may need to wait three or four days for the rock to completely dry.

  • If the ground and rock at the base of a cliff or route is wet the day after a storm, then there is probably subsurface moisture and you shouldn’t climb. It’s the same if the trail to the cliff is wet and muddy.

  • If you do, you risk breaking off key handholds, damaging footholds, and wearing grooves with your rope in the sandstone. Also remember that cams can fail in wet cracks!

  • It will dry slowly if there is high humidity, overcast sky, little direct sunlight, and little or no wind. Remember that snow, which melts slowly off ledges, wets the rock and then freezes at night creating soaked rock that is very susceptible to damage when climbed.