Severe weather includes tornadoes, earthquakes, tsunamis, floods, and volcanic eruptions. It can occur when tectonic plates rub together or due to other natural effects. Weather forecasters monitor conditions around the clock to measure severe weather. Floods happen when heavy rain overwhelms rivers and streams, spilling water onto land. The effects of severe weather like tornadoes, cyclones, tsunamis, droughts, and floods can be very damaging.