
Heat waves are dangerous. They can lead to heat exhaustion or heat stroke, which could prove fatal. But in the rush to avoid those dangers, hidden perils remain.
A stretch of warm weather officially becomes a heat wave when a location faces two or more days of temperatures higher than the historical averages for that area. Those standards can change, depending on the region. A stretch of triple-digit temperature days in June may be average for Death Valley, but the same temperatures farther north might shatter all-time records.