It’s summer in North America, and it’s hot. That’s usually a good thing. Canadians and people living in the northern states spend long winter months looking ahead to their a break from the cold. They are happy to relieve the discomfort of hot summer days by cooling down with dips in the pool and picnics in the shade. But there’s hot, and there’s really hot. And it looks as if really hot, the dangerous and deadly kind, is the type of heat we can expect for the foreseeable future.
In a recent analysis of world temperature and precipitation, the National Atmospheric and Oceanic Administration (NOAA) reported that “the combined average temperature over global land and ocean surfaces for June 2015 was the highest for June in the 136-year period of record.” They also reported that the period July 2014–June 2015 the warmest 12-month period in that same 136-year time frame. NOAA associated the current conditions to an ongoing and strengthening El Niño and stated that there is a “greater than 90 percent chance that El Niño will continue through Northern Hemisphere winter 2015/16, and around an 80 percent chance it will last into early spring 2016.”
The fact that June was the hottest month on record comes as no surprise to the parts of North America that have been suffering through recent heat waves. A heat wave is a prolonged period of excessive heat, generally 10° F ( 5.5° C) or more above average, often combined with excessive humidity. While this year’s El Niño has played a large part, the impacts have been magnified by the effects of global climate change. Regionally, there are also other factors at play.
A University of Birmingham research project studying health impacts of heat waves in urbanized areas identified areas where city centers were up to 13° F (7°C) hotter than the surrounding countryside. This “Urban Heat Island Effect” occurs in built-up areas when large quantities of concrete and asphalt absorb sunlight and store energy during the day and release it slowly at night. Polluted city air can also trap heat and amplify the effects of a heat wave. In an increasingly urbanized world, this is a significant added threat.
The human body can experience considerable physical stress when temperatures and humidity rise. Everyone is at risk to some degree, but extreme heat, more than any other type of severe weather, can impact the health of vulnerable members of a population. The very old and the very young are at increased risk, as are overweight people and those whose health is already compromised by sickness or disease. In recent years, excessive heat has caused more deaths than all other weather events, including floods. However, with a bit of knowledge of the risks, and a little advance preparation, the odds of surviving are greatly improved.
Preparing for a Heat Wave
1. Listen to local news and pay attention to weather conditions; be aware of both the temperature and the heat index. The heat index is the temperature the body feels when the effects of heat and humidity are combined. Exposure to direct sunlight can increase the heat index by as much as 15° F (8° C).
2. Understand the following terms you might hear during a weather forecast:
- Excessive Heat Watch – Conditions are favorable for an excessive heat event to meet or exceed local Excessive Heat Warning criteria in the next 24 to 72 hours.
- Excessive Heat Warning – Heat Index values are forecast to meet or exceed locally defined warning criteria for at least 2 days (daytime highs = 105-110° F, 40-43° C).
- Heat Advisory – Heat Index values are forecasting to meet locally defined advisory criteria for 1 to 2 days (daytime highs = 100-105° F, 38-40° C).
3. If you have any type of air conditioner (window unit, swamp cooler, or central air) make sure it is in working order.
4. Make sure your home is well insulated – this helps keep heat in during the winter and heat out during the summer.
During a Heat Wave
Keep your house as cool as possible:
- Place temporary tin-foil reflectors in the windows to reflect sunlight.
- Cover the windows in your home that receive morning and afternoon sun. (Closing drapes during the day will make a difference, but outside awnings and louvers will stop the heat before it hits the window.)
- If the temperature drops in the evening, open all doors and windows to promote as much air circulation as possible. When the sun rises, close everything again to keep the indoors cool for as long as possible.
- Eliminate extra sources of heat such as incandescent light bulbs, computers, or appliances left running. Eat foods that do not require you to use the oven or stove to prepare.
Keep yourself cool:
- Stay indoors to reduce your exposure to the heat. Head downstairs. Hot air rises, so the lower levels of a home will be cooler than the upper levels.
- If you do not have air conditioning consider spending the warmest part of the day in public buildings such as libraries, schools, movie theaters, or shopping malls. Many cities extend the hours of public buildings during a heat wave. Some cities also set up neighborhood cooling centers to help people cool down.
- Use fans to promote air circulation through your home. Circulating air can cool the body by increasing the perspiration rate of evaporation.
- For a homemade “air conditioning” system, sit in the path of a fan that is aimed at a pan filled with ice or water. Soak your feet, wear a wet bandana or towel around your neck, or take cool showers or baths throughout the day.
Keep yourself healthy and safe:
- Stay well hydrated; you’ll need to consume more water than you usually do when it’s hot. Drink sufficient amounts of fluids before you feel thirsty to prevent dehydration. Avoid alcoholic beverages and caffeine, as these can act as diuretics and promote dehydration.
- Eat appropriately. It’s important to keep eating but adapt your eating habits. Eat well-balanced and light meals regularly, rather than two or three large meals. Large or protein-packed meals take more work to digest which could cause your body temperature to increase.
- Heat can kill by pushing the human body beyond its limits. In extreme heat and high humidity, evaporation slows down, and the body must work extra hard to maintain a normal temperature. Understand the difference between heat cramps, heat exhaustion, and heat stroke. Heat stroke is a severe medical emergency and can be life-threatening.
- Heat waves can cause blackouts and power outages, especially in areas that experience the Urban Heat Island effects as explained above. Heat waves have also been known to start wildfires and bushfires across drought-stricken areas. Go to a designated public shelter if your home loses power during periods of extreme heat. Stay safe.
- Federal Emergency Management Agency
- National Climatic Data Center
- Red Cross