Warning: Mt. Shasta's weather is variable and the mountain often makes it's own weather too

Mt. Shasta's weather is variable. The exposure to storms from the Pacific can result in high winds and heavy snow accumulations. Major storms can certainly occur at any time of the year and Mt Shasta's solitary position intensifies any existing weather conditions. John Muir nearly lost his life due to hypothermia on Mt Shasta and the mountain is more than capable of dishing out some pretty extreme conditions for the modern day hiker / climber
end partial quote from:
https://www.timberlinetrails.com/ShastaApproach.html

Yes. I have experienced 100 mph winds on top of mount Shasta and I have also experienced Hail on days that should be 80 to 100 degrees in the summer to the point where I had to hide from the hail under trees with my family and friends not to be injured physically.

I have done really stupid things "looking back now" like drive my VW Bug in 1970 on Christmas vacation from college to Mt. Shasta from San Diego driving 14 hours through Palos Verdes to pick up a then UCLA Student and then we picked up a Sacramento State Student in Chico where his mother lived and wound up arriving in the dark in a blizzard at Bunny Flats thinking we were okay to hike on snow shoes to Horse Camp in the dark (it was NOT okay) but we were between 20 and 22 years old each then and were adventurers who almost didn't survive the next 24 hours.

Why?

Because we got caught in a 3 foot deep whiteout blizzard in between Bunny Flats and Horse camp that night on Snowshoes.

And if one of us hadn't just taken a survival course in how to dig a snow cave to survive such an experience we likely would have all frozen to death from exposure that night because we just were not prepared for what we were facing. 

Even after digging out of our snow cave for the night when we finally reached my car all I could see was the top 3 inches of the aerial so if the snow plow hadn't come by then we likely wouldn't have made it out of that problem either. 

So, by some miracle of youth and ballziness we survived that experience by driving down and getting a hotel room and bathing in the hottest water we  all could stand one at a time for 4 days.

Today people would check themselves into a hospital for exposure or something but we grew up in a different time than now.

All the joints in my body hurt for several years after that from almost freezing to death and I still have lost most of my temperature sense in my body where I'm not always sure when I'm hot or cold when it is useful to know such things.

But, somehow life goes on even after all that.