2018 is likely to be the world's 4^th warmest year on record; cooler than 2015, 2016 or 2017, but warmer than any year prior to 2015. Temperatures have been above average over most parts of the world, with the only large area with below-average temperatures over parts of Canada. Sea ice extent continued to be well below average in both the Arctic and Antarctic.

A major drought and exceptional warmth affected many parts of northern and western Europe through the middle of 2018, with many regions setting records for seasonal mean high temperatures and low rainfall, especially in the Nordic and Baltic countries, Germany, Poland and the Netherlands. There were prolonged heatwaves in July and early August, with significant agricultural losses, river transport disruptions, and substantial wildfires. January to October was the warmest on record for Europe overall (despite a major cold outbreak in late February and early March) and for many countries. Other major droughts occurred in eastern Australia, Argentina and Uruguay, but drought conditions eased in east Africa and in the Cape Province of South Africa. It was a record-breaking wildfire season in western Canada, and Greece experienced the worst loss of life in a wildfire globally since the 2009 Black Saturday fires.

Japan had a sequence of severe weather, including destructive floods, a record-breaking heatwave (which also affected the Korean peninsula) and the strongest typhoon landfall since 1993. Globally 2018 was one of the most active tropical cyclone seasons on record, with major impacts including those of Florence and Michael (United States) and Mangkhut (Philippines, Hong Kong and China). Active monsoon conditions brought destructive flooding in August to the southwest Indian state of Kerala, while major Mediterranean storms had widespread impacts on Greece, Tunisia and Libya in September, and Italy and neighbouring countries in October.