This bulletin describes safety considerations for lightning and hail. While accompanying thunder is not considered
a hazard itself, it can be a warning that there’s a potential for lightning or hail.
Lightning results from the buildup and discharge of electrical energy in clouds. Lightning can strike several
kilometres from an associated thunderstorm. It can strike even when there are no clouds or rain.
Hail is usually associated with thunderstorms. It is caused by freezing rain and can range in size from 5 mm (0.2 in.)
to 15 cm (6 in.).