Precipitation (rain and snow) varies naturally from year to year and from decade to decade, influenced by the El Niño-Southern Oscillation (ENSO and other climate drivers.  
In addition to natural variability, it is likely that climate change is also influencing the frequency and intensity of extreme precipitation because warm air can hold more moisture.  
Greater warmth also speeds up the water cycle, which is likely to lead to increased evaporation and heavier rainfall. More intense rainfall during tropical storms and rising sea levels poses a particular risk to coastal regions.
The changes in the water cycle will not be uniform.  The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase during the 21st century, although there may be regional exceptions, according to the Intergovernmental Panel on Climate Change.

A WMO survey in 2010 found that the largest number of national records for 24-hour extreme precipitation occurred in the previous two decades – 1991-2010. Floods were the most frequent extreme event.

Floods in Pakistan killed more than 2 000 people and affected 20 million in 2010, the wettest year on record.

The Southeast Asian floods of 2011 caused economic losses of more than US$40 billion, mostly in Thailand, and were responsible for more than 800 deaths. A flash flood in southern Brazil in January 2011 claimed more than 900 lives.

Floods and landslides in Uttarakhand, northern India, in June 2013 left more than 5 800 people dead or missing.  Floods in central Europe in May and June 2013 caused economic losses of more than US$20 billion.

Typhoon Haiyan hit the Philippiines on 8 November. It killed at least 6 300 people, mostly from the tsunami-like storm surge. The island of Leyte had rainfall totals greater than 500mm, with a peak amount of over 685 mm  because of Haiyan and another tropical storm.

Extensive flooding in the Paraná river basin in central South America in June and July 2014 affected more than 700 000 people in Paraguay, western Brazil and northern Argentina.

Destructive flooding occurred in many parts of the world in 2015, causing major casualties and humanitarian impacts, heavy economic losses or both.

The powerful El Niño meant that 2015 was wet in many subtropical parts of South America (including Peru, northern Chile, Bolivia, Paraguay, southern Brazil and northern Argentina), and in parts of the southern United States and northern Mexico. Overall, global precipitation in 2015 was close to the long-term average, but there were a number of extreme events during the year. There were many instances in 2015 of 24-hour totals exceeding the normal monthly mean.

Fast Facts

Greatest 1 Min rainfall: 31.2 mm 4.7.1956, Unionville, MD, USA

Greatest 12-hour rainfall: 1.144 m, 7-8.1.1966, Foc-Foc, La Réunion

Greatest 12-month rainfall recorded was 26.47m from 8/1869-7/1861 in Cherrapunji, India


2015 at a Glance

Regions tab