Cold wave and Heat wave

A cold wave is a weather phenomenon that is illustrious by marked cooling of the air, or the invasion of very cold air, over a large area. It can also be a prolonged period of excessively cold weather, which may be accompanied by high winds that cause excessive wind chills, most important to weather that seems even colder than it is. Cold waves can be preceded or accompanied by significant winter weather events, such as blizzards or ice storms.
A heat wave is a prolonged period of extremely hot weather, which may be accompanied by high humidity. There is no general definition of a heat wave; the term is relative to the usual weather in the area. Temperatures that people from a hotter climate consider usual can be termed a heat wave in a cooler area if they are outside the normal climate pattern for that area. The term is useful both to routine weather variations and to extraordinary spells of heat which may occur only once a century. Severe heat waves have caused catastrophic crop failures, thousands of deaths from hyperthermia, and widespread power outages due to increased use of air conditioning.