A September 28, 2015 article in The Spectrum newspaper discusses 10 dangers that “can ruin a hike”.
While focused on hiking dangers in southern Utah, most, if not all, of the list is applicable to hiking in any location, particularly for Scout units where youth are involved.
The 10 identified hiking dangers are the following:
(1) Giardia;
(2) Poisonous plants;
(3) Blisters;
(4) Sunburn;
(5) Falling;
(6) Getting lost;
(7) Cold temperature;
(8) Flash floods;
(9) Dehydration/heat exhaustion; and
(1o) Lightning.
These dangers are real. It is not difficult to find stories on the web directed to injuries and/or rescues resulting from lightning, dehydration, heat exhaustion, flash floods, lost hikers, and hikers becoming injured due to falls from a height.
Indeed, stories involving Scouts suffering from the effects of falling from heights, getting lost, cold temperatures, flash floods, dehydration, heat exhaustion and lightning have appeared on the web. The author is also aware of an instance involving a Philmont crew which, at the conclusion of their trek, suffered from Giardia poisoning due to their failure to properly purify their drinking water. 
Experienced and trained BSA volunteer leaders should thus be able to both anticipate, and deal with, such risks and dangers, several of which are specifically dealt with by the Guide to Safe Scouting, and Weather Hazards on-line training.
To be forewarned is to be forearmed (hopefully)! Safe hiking.