Abstract:The concentration of greenhouse gases kept increasing in 2018, while the global mean temperatures were 0.99℃ above pre industrial levels, which was the fourth warmest year on record. The total amonnt of global glacier has been decreasing continuously for 31 years, and the sea ice extent of Arctic sea and Antarctic lay at a low level on record throughout the year. Global sea surface temperatures were positive above the 1981-2010 average, and the global mean sea level was rising steadily. The ocean heat content reached a new record highs, with the intensified impact of ocean acidification. Many significant weather and climate events occurred in 2018 and caused serious human casualties and socio economic losses, including a very active tropical cyclone season in Northern Hemisphere, the persistent dry and hot summer in large parts of Europe, the severe floods in Southwest India, the severe drought in eastern Australia, the cold and heavy snowstorms in Europe and America, as well as the wildfires and severe convective weather events in many parts of the world. This paper systematically summarizes the major global weather and climate events in 2018 and their impacts, and focuses on the possible causes of the worst flooding in India in the recent 100 years and the explosive low temperature, rain snow and freezing events on the east coast of the United States, the two typical weather events analysis results show that under the combined action of the strengthening and persistent South Asia summer monsoon, northwestward monsoon trough position and strengthening Somali jet in August, the water vapor transport to India was in great quantities from southern Indian Ocean and Arabian Sea, causing continuous heavy rainfall and resulting in the worst flooding in India in recent 100 years. In early January, under the combined influence of coupled jet structure, strong ocean temperature gradient and high temperature surrounding cyclones, the winter windstorm Grayson intensified explosively, resulting in severe coldwave and snowstorm in the east coast of the United States.