A heat wave is a period of abnormally hot and usually humid weather. Average max temperatures exceed the normal weather conditions of a region. If for instance Kenya's former Central province has an average temperature of 24C, then temperatures of 40C would imply a heat wave is in place.
Heatwaves form when high pressure from about 3000-7600M remains over a region for several days. They are common in summer.
Some effects on health are:
Heat strokes(hyperthermia), ichargiwe mostly affects older adults, very young children and overweight people.
Heat rash- affects heat ducts
Heat edema- swelling of limbs, ankles
Heat cramps- involuntary spasms of large muscle groups.
The European heat wave in 2003 killed 70,000 people.
This week in Pakistan, as of today, more than 700 are dead.
Between April and May this year, a heat wave in India killed more than 2200 people. Temperatures ranged between 45-47C.