Being Prepared for Summer

Summer weather can change rapidly. Be alert to the latest forecasts, stay aware of the weather around you, plan ahead for possible emergencies, and take appropriate steps to protect yourself and your family from the risks of summer severe weather.

For more detailed information on summer safety, visit the following links:

• Planning Ahead
• Taking shelter
• Lightning safety
• Hail safety
• Storm Surge Safety
• Heat and Humidity Safety

Planning Ahead

Having a storm readiness plan in place saves valuable time if severe weather strikes. Take the opportunity now to choose the best shelter in your home and office, and make sure all concerned know where it is. Choose a meeting place to gather after the storm to ensure that everyone is safe and accounted for.

Maintain an emergency pack with a battery-powered flashlight, a radio (with Weatheradio capability preferably), tools for emergency repair, food supplies, a first aid kit, blankets and extra clothing. Keep your car gas tank full, in case gas stations close down after a storm. When a warning is issued, stay calm and follow your plan.

For more information on how to prepare yourself and your family for an emergency situation, visit the Government of Canada’s 72 Hour Campaign.

Taking Shelter

When there is a threat of high winds, as in the case of a severe thunderstorm or tornado, your first priority is to take shelter. If it is safe to do so, bring livestock and/or pets indoors, close all windows and doors, and secure loose outdoor objects or move them inside.

Go to the basement or to a small interior room in the centre of the house, such as a closet, bathroom or hallway, on the lowest floor of the building. If this is not an option, take cover under a stairway or sturdy table and use a cushion or mattress to protect your head. Stay away from all windows, doors and exterior walls, in particular those facing the storm, and avoid buildings with large, unsupported roofs such as arenas, supermarkets, and barns. If you are boating or swimming, head for land immediately.

Do not travel. If you are in your car, open the windows slightly and park off the road with your brakes set, away from tall objects and power lines. Do not leave your car if there are downed lines nearby. In the event of a tornado, abandon your vehicle and move at a right angle to the storm’s path. If this is not possible, find a low-lying area, such as a ditch, and lie flat. Hang onto a small tree or shrub if you can.

Lightning safety

If you can hear thunder, you are within lightning striking distance. Take shelter immediately, preferably in a house or all-metal automobile (not convertible top) or in a low-lying area.

When there is lightning nearby, head indoors immediately. Stay away from electrical appliances and equipment, doors, windows, fireplaces, and anything else that will conduct electricity such as sinks, tubs and showers. Avoid using a telephone that is connected to a landline.

If you are in your car, do not park under tall objects that could topple, and do not get out if there are downed power lines nearby.

There is no safe place outdoors during thunderstorms. As such, in situations where you find yourself outside during a thunderstorm, it is best to quickly get to a safe indoor venue as soon as possible, or a car if an indoor area is not available. If you find yourself stuck outside with no other safe option, keep away from trees and other hazards, and drop to your knees, bend forward so your head is lower than your back (but not touching the ground) and put your hands on your thighs. Do not lie flat on the ground. Remember that even if you do this, being exposed outside during a thunderstorm with lightning can lead to serious danger, injury and even death.

If caught on the water in a small boat with no cabin, quickly get to shore. Boats with cabins offer a safer but still not ideal environment.

People who have been struck by lightning do not carry an electrical charge and can be safely handled. Call for medical assistance immediately and, if breathing has stopped, administer mouth-to-mouth or cardio-pulmonary resuscitation.

Hail safety

When hail threatens, move indoors and bring livestock and/or pets into a sheltered area. Stay away from windows and glass doors. If possible, move vulnerable items such as cars, equipment and machinery to a protected area as well. If you are caught outdoors, reduce your chances of injury by crouching down, facing away from the wind, and protecting your head and neck.

Storm Surge Safety

In the event of a storm surge, avoid coastal areas, particularly those prone to flooding, and seek higher ground. This Public Safety Canada website offers detailed information on what to do in the event of a storm surge.

Heat and Humidity Safety

It is important to stay safe during such extreme temperatures. Avoid working or exercising intensely if it is very hot or humid outside, and head for cooler conditions if your body becomes overheated. If working outdoors is an absolute necessity, drink plenty of liquids and take frequent rest breaks. Be sure to maintain salt levels in your body and avoid high-protein foods. Also ensure that pets are protected from the heat and have plenty of water to drink. Watch for signs of serious medical conditions, such as heat exhaustion and heat stroke.

• Relative humidity
• Humidex
• Guide to summer comfort
• See the humidex table
• Humidity in the forecast  
• Frequently asked questions

Relative humidity

Relative humidity is the amount of moisture that the air contains compared to how much it could hold at a given temperature. A figure of 100 per cent relative humidity would mean that the air has become saturated. At this point mist, fog, dew and precipitation are likely.

Relative humidity is normally at its maximum when the temperature is at its lowest point of the day, usually at dawn. Even though the absolute humidity may remain the same throughout the day, the changing temperature causes the ratio to fluctuate.

Humidex

The humidex is a Canadian innovation, that was first used in 1965. It describes how hot, humid weather feels to the average person. The humidex combines the temperature and humidity into one number to reflect the perceived temperature. Because it takes into account the two most important factors that affect summer comfort, it can be a better measure of how stifling the air feels than either temperature or humidity alone.

The humidex is widely used in Canada. However, extremely high readings are rare except in the southern regions of Ontario, Manitoba and Quebec. Generally, the humidex decreases as latitude increases. Of all Canadian cities, Windsor, Ontario has had the highest recorded humidex measurement: 52.1 on June 20, 1953. The hot, humid air masses which cause such uncomfortable weather usually originate in the Gulf of Mexico or the Caribbean.

Guide to summer comfort

Range of humidex: Degree of comfort

• Less than 29: No discomfort
• 30 to 39: Some discomfort
• 40 to 45: Great discomfort; avoid exertion
• Above 45: Dangerous; Heat stroke possible

An extremely high humidex reading can be defined as one that is over 40. In such conditions, all unnecessary activity should be curtailed. If the reading is in the mid to high 30s, then certain types of outdoor exercise should be toned down or modified, depending on the age and health of the individual, physical shape, the type of clothes worn and other weather conditions.

If working outdoors is an absolute necessity, drink plenty of liquids and take frequent rest breaks. In hot, humid conditions, there is a considerable risk of heat stroke and sun stroke.

During the dog days of summer, remember that animals also feels the heat. When the humidex is high, take special care to ensure that your pet is well-protected from the heat and has plenty of water to drink. Also remember to never leave pets in hot vehicles, even with the window down. On extremely hot days, the inside temperature of a car can be several degrees warmer than the air outside and it is therefore never safe to leave pets or children – even for a few minutes.

Humidex table

Legend

Humidex	Degree of Comfort
20 - 29	No discomfort
30 - 39	Some discomfort
40 - 45	Great discomfort; avoid exertion
46 and over	Dangerous; possible heat stroke

 

Humidex Temperature and Relative Humidity

 

Humidex for Relative Humidity from 100% to 65%

Relative Humidity (%) Temperature (°C)	100%	95%	90%	85%	80%	75%	70%	65%
21 °C	29	29	28	27	27	26	26	24
22 °C	31	29	29	28	28	27	26	26
23 °C	33	32	32	31	30	29	28	27
24 °C	35	34	33	33	32	31	30	29
25 °C	37	36	35	34	33	33	32	31
26 °C	39	38	37	36	35	34	33	32
27 °C	41	40	39	38	37	36	35	34
28 °C	43	42	41	41	39	38	37	36
29 °C	46	45	44	43	42	41	39	38
30 °C	48	47	46	44	43	42	41	40
31 °C	50	49	48	46	45	44	43	41
32 °C	52	51	50	49	47	46	45	43
33 °C	55	54	52	51	50	48	47	46
34 °C	58	57	55	53	52	51	49	48
35 °C		58	57	56	54	52	51	49
36 °C			58	57	56	54	53	51
37 °C					58	57	55	53
38 °C							57	56

Humidex for Relative Humidity from 60% to 20%

Relative Humidity (%) Temperature (°C)	60%	55%	50%	45%	40%	35%	30%	25%	20%
21 °C	24	23	23	22
22 °C	24	24	23	23
23 °C	27	26	25	24	23
24 °C	28	28	27	26	26	25
25 °C	30	29	28	27	27	26
26 °C	31	31	29	28	28	27
27 °C	33	32	31	30	29	28	28
28 °C	35	34	33	32	31	29	28
29 °C	37	36	34	33	32	31	30
30 °C	38	37	36	35	34	33	31	31
31 °C	40	39	38	36	35	34	33	31
32 °C	42	41	39	38	37	36	34	33
33 °C	44	43	42	40	38	37	36	34
34 °C	47	45	43	42	41	39	37	36
35 °C	48	47	45	43	42	41	38	37
36 °C	50	48	47	45	43	42	40	38
37 °C	51	50	49	47	45	43	42	40
38 °C	54	52	51	49	47	46	43	42	40
39 °C	56	54	53	51	49	47	45	43	41
40 °C		57	54	52	51	49	47	44	43
41 °C			56	54	52	50	48	46	44
42 °C				56	54	52	50	48	46
43 °C					56	54	51	49	47