What are the extreme weather? The standard of extreme weather?

If you say "extreme" in the language of ordinary people, it is "rare". For example, our usual temperature is 20 degrees, which will drop to a few degrees below zero in winter and may be more than 30 degrees in summer. If the temperature exceeds 40 degrees, it is rare. If the local rainstorm is heavy, it is also extreme weather. If the probability is relatively small, such probability events below 5% are extreme weather and climate events, including gale, rainstorm and blizzard, because their probability is relatively small. If they are beyond the normal range, we consider them as extreme weather and climate events.

For example:

2007 is coming to an end. Looking back on the unsettled weather this year, we have experienced too many storms: in early March, a severe snowstorm hit the northeast of China; Spring drought in North China and Northeast China; In July, the Huaihe River Basin was hit by a basin-wide flood, which was second only to 1954 since the founding of New China. Chongqing and Jinan experienced the worst rainstorm and flood since meteorological records were recorded. During the "Eleventh" Golden Week, the super typhoon "Rosa" swept through Zhejiang and Fujian provinces with wind and rain.