Seasons.  Mount St. Helens is part of the Cascade Range where deep snow accumulation occurs during some winters.  Standard wisdom has divided the year into the tourist season (mid-May to mid-October) and the non-tourist season (mid-October to mid-May).  Last winter (2007-2008) the local paper reported snow drifts measuring 35’ at Loowit Viewpoint (Milepost 51 on our highway).  It further said that the snow was so deep on the east side of MSH that the road to Spirit Lake (FR 99) may not be open until July.  Precipitation averages about 140” annually at MSH and about 50” annually where the 7WM is.  December and January are usually the two wettest months (11” average) although November and February can be just as wet.  Because of unpredictable weather Johnston Ridge Observatory and Weyerhaeuser Forest Learning Center are closed during the non-tourist season.  No great effort is made to plow the last seven miles of the highway (rising to 4200’) once heavy snows set in.

People call about visiting during the non-tourist season.  The 7WM is located at an elevation of about 600’, in the lower Toutle Valley, and is rarely snowed in.  So we encourage people to make the 7WM a final destination any time of the year.  One of our hikes, the Sediment Dam hike, is also accessible most of the year.  So people can visit the 7WM and even go on the Sediment Dam hike during part of the non-tourist season.  However, a driving rain, high winds or occasional snow falls may make even the Sediment Dam hike unadvisable.

Because of the small number of visitors during the non-tourist season, we ask people to make an appointment during that time of year, even though the custodians are on site and have the Museum open most of the time.

Hours.  During the tourist season the 7WM is open most Mondays-Saturdays from 9-6 and by appointment at other hours and on Sundays.  However, since it is closed a day here and a day there during the tourist season, we urge people to call before coming.

Weather during the Tourist Season.  While clouds may hide the mountain at any time, July and August are the best months for mountain viewing.  Strong winds can spoil otherwise nice days in October.  Blowing ash can sting bare legs.  May features about a 50% chance of showers.  That drops to about 30% in June, but there are still a lot of clouds.

As summer transitions into fall there is frequently a few days of rain near the end of August or the first part of September.  ICR has sponsored a tour of MSH every 4-5 years in recent memory, coming after the summer graduate school has completed its work, usually towards the end of August, and each time the tour party has been greeted with inclement weather.

If your schedule allows you to watch for favorable weather and visit during such a period, that might be a good strategy.  Some summers provide several months without rain.  Even on a hot day clouds can materialize over the mountain in minutes, usually later in the day.  But sunny days are glorious—even in the winter when the mountain can be seen clear and dressed in snow.