Heat waves which are prolonged periods of excessively hot and usually highly humid weather, cause much discomfort and are even dangerous to some. The elderly, the very young and those with respiratory and other health problems are more at risk.
It is important to limit physical activity to a minimum, seek cooler areas either indoor with air conditioning or in in the shade outside. Use fans if you don't have air conditioning.
Check to see what the air quality is forecasted for the day, as well as the U.V. Index. These are other things that make a difficult time worse. At the time I had originally written this article it was on July 6, 2010 and was experiencing a heat wave. I didn't have air conditioning and it was 30˚ C (88˚ F) in my apartment. Outside it was 27˚ C (81˚ F) at 9:13am. I had tried to ventilate with fans overnight to recycle the air inside, but it didn't seem to work. The air was too warm overnight.
They were announcing 32˚ C (90˚ F) with the humidex at 40˚ C (104˚ F) for the afternoon but that it could go higher. The U.V. Index was forecast to be at 11+ or extreme. The air quality wasn't high either. The heat wave was there since the day before and was expected to continue till the weekend, when a cold front (excellent!) is expected to move in.
Power grids are often overwhelmed due to increased use of fans and in particular air conditioners. So be prepared to manage without electricity if a blackout happens. Have supplies aside, even though these blackouts generally do not last very long.
I mentioned that it is important to limit physical activity above, which is one thing to do. But you need to remain properly hydrated as well. Do not wait until you are thirsty to have a drink of water.
Avoid alcohol which will dehydrate you even further. Water is best. Eat normally to replace any electrolytes that have been lost through sweating and urination.
This normally isn't a problem, but can be if you
are going to be particularly active for a reason or other despite the
heat wave. Top level athletes know their bodies very well, and know how
and when to replace their electrolytes. The average person only needs to
eat normally, given the salt content in today's foods. If you are not
certain, err on the side of caution and take appropriate actions to
prevent heat related problems. Don't take any unnecessary risks!
If you have medical problems beware as you may deteriorate more rapidly. There was a 14 year old boy that died at a water park because he had a heart problem. The heat seemed to have made his condition worse and he died. Do not take any chances. There will always be another day for your jogging or other activity.
Monitor your condition closely to avoid heat related injuries such as heat cramps, heat exhaustion and heat stroke which is the worst. If you are not careful you can progress from heat cramps which is the least serious to heat stroke in a very short time, so be careful.
If you must go outside wear loose, lightly colored long sleeved clothing with pants, a wide brimmed hat and sunblock with an SPF rating of 25 or higher for any exposed areas. Re-apply as required by the manufacturer. This is one of those times to wear cotton.
Don't forget your eyes and wear a pair of good sunglasses. Get the ones that block out harmful UV rays and that cover the sides of your eyes as well for extra protection.
If you have to work indoors or outdoors during a heat wave:
Be particularly vigilant for your well-being and if you have responsibility over others, their well-being as well. Have a look here for more information on how to cope during a heat wave if you have to work during this time.
If you are in a survival situation during a heat wave:
In the heat you want to shelter yourself from the sun, hydrate yourself and limit your activities until it cools down. It all depends on the circumstances, but take proper precautions to avoid a heat related injury. If there is a breeze, take advantage of it when selecting a shelter site. If you have some water that you can spare, wet your clothing to take advantage of the convective and evaporative cooling effect it will provide. However, if water is scarce save it for drinking.
Also, it is important to not have too much
wind blowing across your skin as this will dry you off and negate the
cooling effect of sweat. Find the right balance. Always hydrate yourself
to replace water lost through sweating. It's all about giving your body what it needs to properly thermoregulate.
Do not take off clothing to the point that your skin will be exposed to the sun. The sun can sunburn and dry out your skin, the largest organ in the body that is needed to evacuate excess heat to maintain a proper body core temperature. Permit some sweating in hotter temperatures! It may feel uncomfortable, but it is necessary. You must know the feeling of getting out of the water after taking a swim and feeling cooled off as a breeze blows on you. The principle is the same. The sweat is a cooling mechanism for the body, more than the wind alone can provide without it. As I mentioned before, take advantage of any breeze or create it by 'fanning' yourself. Improvise!
Also apply the other principles involved in the elements of survival, depending on the circumstances.
Here are some links to help you learn more about heat waves.
1. Wikipedia - Heat Wave
You can download the list on the Downloads page called Measures to Take During a Heat Wave. You may print it to have a copy on hand.