It looks like El Nino is back – what will it mean for our weather?

Is the world's weather about to change? And will it get better or worse?

• Duncan Graham-Rowe
• The Guardian, Tuesday 14 July 2009
• Article history

With sea-surface temperatures in the eastern Pacific at least 1C above average, it looks like El Niño is back. This cyclic weather system normally occurs once every two to seven years, and last reared its head in 2007. The current El Niño is forecast to last until the end of winter. So what could it have in store for us and the rest of the world?

Britain It's still too early to say whether last month's hot weather was a sign of El Niño, partly because the system affects the UK and western Europe somewhat unpredictably. However its complex knock-on effects on the global weather system do tend to bring more extreme weather to our shores, so even if the sun continues to shine this summer, the chances are we can also expect a colder, wetter winter, and an increased risk of flooding.

The US It's not all bad news. Through its influence on tropical winds feeding into the Atlantic, El Niño also helps to reduce both the number and severity of hurricanes hitting the east coast of the US and the Gulf of Mexico. In the eastern Pacific the opposite is the case. The west coast of the US can also expect increased rainfall stretching inland as far as the Rocky Mountains.

Western Pacific In anticipation of the dry spells that El Niño normally brings to the western Pacific, authorities in the Philippines have urged farmers to plant their rice crops early this year, to make use of the available water. Australians, meanwhile, will need to prepare for a summer of bush fires and poor air quality.

Africa The impacts here are perhaps least predictable. The continent faces the grim prospect of severe drought, particularly in central regions, or of being deluged by rain in the east and south. Either way the impact carries a health warning. With drought comes famine, while heavy rain leads to an increased risk of malaria, Rift Valley fever and outbreaks of cholera.