The odds of being struck by lightning in Canada are lower than one in a million. Yet each year, about 6 to 12 Canadians are killed by lightning and many more are injured. One well-known lightning guideline is the "30-30" rule: Take appropriate shelter when you can count 30 seconds or fewer between lightning and thunder, and remain sheltered for 30 minutes after the last thunder.
When there are fewer than 30 seconds between the flash of lightning and the rumble of thunder, you should seek immediate shelter in a well-constructed building. If no such building is nearby, then the best choice is to get into a hard-topped vehicle such as a car, van or RV. If you are caught outside and cannot quickly get to a building or vehicle, then you should do the following:
Avoid being the tallest object around;
Avoid being NEAR the tallest object around (i.e. an isolated tree);
Avoid being near objects that conduct an electrical charge (metal fence, power lines, golf clubs, fishing rod, etc.);
Get out of, or off, the water.
Maintain lightning safety precautions for 30 minutes after the last flash of lightning or rumble of thunder. There have been a number of documented cases of lightning striking the ground many kilometres away from a thunderstorm, even though the storm may be moving away.
A good resource is Environment Canada Lightning Safety.