In their 1996 Position Stand document "Heat and Cold Illnesses During Distance Running," the American College of Sports Medicine made this statement:
"(We) recommend that race officials consult local weather archives and plan events at times likely to be of low environmental stress to minimize detrimental effects on participants."
It is the contention of the Zunis Foundation that this good advice should be taken by the organizer of any sporting event, be it a football practice, a tennis tournament or a distance running competition. The reasons for this sentiment are twofold: First, the greatest goal of every athlete, every coach and every event organizer should be to avoid injury. Scheduling competitions in conditions likely to produce injuries is a practice which must be vigorously rejected. Secondly, competition in adverse conditions will result in a low quality of competition. This is most easily quantified in distance running, in which a clear detrimental effect of hot weather on performance has been repeatedly shown.
Unfortunately, the ability of most of us to "consult local weather archives" is severely limited. At best, one may find out the "average" and "extreme" high and low temperatures for a given date for a given large city from an Almanac or from the Internet. Even these sources are not easy to find and may not cover the city in question. They never provide detailed information such as the way that temperatures vary through the day. More sophisticated measures of heat stress such as Heat Index or Wet Bulb Globe Temperature are likewise never available.
To obtain this information from the National Weather Service or from a private weather research company would cost, as best we can determine, at least $1000 per site per search. Obviously, this figure is simply beyond the reach of nearly every event organizer. By comparison, the 1996 Atlanta Olympics commissioned a prominent exercise physiologist to carry out climate profiling before the Games, and his findings led to event re-scheduling.
The Zunis Foundation provides this very expensive information to you free of charge for 101 US cities at this Web site. Information for an additional 140 cities is available by mail for a small fee from The Chart Store.
So What's The Point?
The point is this: You as a coach or an event organizer will usually have some scheduling latitude. If it is possible, try to schedule an outdoor event on a day when high heat stress is almost never a problem. If that is not an option, and you must use a day which is potentially dangerous, put the event in a part of the day which is most likely to be safe, or move it indoors. If you are so terribly constrained that you must send athletes out into a furnace, understand what you are doing. Make sure that they have every opportunity to defend themselves against heat injury. Watch them closely for signs of trouble, and make it your goal that not a single one of them will collapse. Make the athletes understand that you reserve the right to stop any of them at any time, and that there is no shame in recognizing limits. You will have to show the courage of true leadership, but it will be worth it.