The opportunity to climb Mount St. Helens in southwest Washington has become very popular, and people are snatching up the required permits very quickly.

The permits went on sale Feb. 1, and in less than 24 hours all of the Saturday and Sunday permits for July and August were sold out, plus many other Saturdays in June and September, a total of 4,249 permits.

The number of permits sold accounted for 21 percent of the total available to summit the volcano.

As of this past week there was still 15,000 permits available from May 15 to Oct. 31, and during this time it is limited to 100 daily.

But, from April 1 to May 14, permits are unlimited, which allow climbers the chance to purchase them based on weather conditions.

Depending on snow conditions, spring and early summer are popular times for skiers and snowboarders.

Those who'd like to coincide their mountain trek with a view of the full moon depending on clear sky conditions should take a look at these dates: April 6, May 6, June 4, July 3, Aug. 2, Aug. 31 (Blue Moon), Sept. 30 and Oct. 29.

The Mount St. Helens Institute also leads guided climbs on Fridays and Saturdays through the summer, including some with a geologist. For details, visit http://mshinstitute.org.

To purchase or reserve a climbing permit, visit http://mshinstitute.org/index.php/climbing/index.

Mark Yuasa: 206-464-8780 or myuasa@seattletimes.com