Talking about the weather used to be the conversation topic of last resort.

Global warming changed all that, but long before we knew about inconvenient truths and emissions trading, it was a cheeky little Spanish boy who kept meteorologists awake at night.

Well, El Niño is back.

The Courier Mail tells us today that the strongest drought-bearing El Niño conditions seen in Queensland for seven years have brought a heat wave to much of that state. The effects of the newest El Niño pattern are showing up across the Pacific, and there is plenty more to come this summer for eastern Australia.

What exactly is El Niño?

El Niño is Spanish for “the boy-child”, a centuries-old reference to Jesus Christ. History tells us that Peruvian fisherman coined the term to describe the warm ocean current off the coast of South America that would arrive close to Christmas.

When it comes to contemporary weather patterns, El Niño refers to periods of strong warm weather, which influences climate around the globe. El Niño’s frigid little sister, La Nina, is known for prolonged cooler weather patterns, or the opposite weather patterns of her brother.

After the weather forces of the yearly seasonal cycle, El Niño is the most powerful force behind global weather patterns.

El Niño events are usually characterised by changes in air pressure around the Pacific, also sometimes referred to as the Southern Oscillation.

What does El Niño do?

In the short term, El Niño increases the chances of eastern Australia experiencing drier conditions between now and the end of summer 2010. This is bad news for the eastern seaboard, already affected by crippling drought, and for water systems such as the Murray-Darling basin.

El Niño events occur irregularly, usually every 2-7 years and lasting 12-18 months. The extreme weather patterns El Niño causes are well known to Australians, including floods and drought.

The stronger the El Niño pattern is, the greater the chance of reduced rainfall, exacerbating drought conditions.

El Niño last visited Australia in 2002 and 2006, and in both cases the system brought about very dry conditions in the eastern states adding to the decade-old drought still in place in much of the country.

However, the arrival of another El Niño pattern is not all bad news. Surfers in Hawaii are currently experiencing waves of up to 16 metres and some of the most exciting surfing conditions seen in the Pacific for decades.

The size of the waves is directly related to the arrival of the latest El Niño system. The Times reports that an El Niño year brings about a large increase of injuries and increased demand on lifesavers patrolling surf beaches across the Pacific.

But for Australians, El Niño is a most unwanted house guest, like to outstay its welcome.