And I don't mean to trivialize Mount Washington, b/c I'd take a mountain of that size VERY seriously. Hence why I'd budget more time to get back to my car than it took me to get where I'm at, even if that means I don't make it to the top. I guess I'm just not sure.... if you plan to hike in good weather (top to bottom), you plan plenty of time, and you stick to marked trails... are you still in serious danger? Like as an amateur hiker should I just never attempt? And I'm that... I'm not serious. I just love a good day hike. Like until this thread I would have totally hiked a marked trail if I started early and carried a stocked backpack on a good day, but maybe no?
A few weeks ago a friend told me she was planning on a hike in the White Mountains, solo. She hadn't done a hike that long in years. She asked me whether I thought she'd be fine, and I replied that as long as there wasn't snow/ice, her pack had the 10 essentials, and the weather was clear, she'd be fine. Her response was that she hadn't even thought of snow but didn't think there was any because there wasn't any where she was.
This is where many people would have stopped seeking information and just gone up and hiked. Technically, my friend did stop seeking information.
I emailed someone who had more recently been up, who told me that anyone attempting the hike right now needed traction for their shoes because the ridge was iced over. At that point, my friend decided to hike something else (she also emailed me her plans, told me she'd text me by x time, and gave me emergency contact info.). It turned out fine.
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In early spring, especially in bad snow years, many people don't realize that even though it looks like spring outside their windows, it can still be winter at the higher elevations 100 miles elsewhere. Additionally, a curious aspect of human nature is that it is not infrequent that when people encounter sketchy terrain or weather, they forge on even when they should turn around, or they underestimate the weather. We suck at decisionmaking when the eye is on the prize and become very focused on the goal, despite warning signs.
My best advice is to get as much information as you can about conditions, terrain, route, and weather beforehand (lots of online hiking forums these days and traditional guidebooks); stay observant of changing weather conditions, the sun/daylight, and your pace; make sure your pack has the 10 essentials in case something freakish happens; and be okay with reaching your personal summit -- it doesn't need to be the actual one.