'Triple dip' La Nina weather event possible by the end of the year

Meteorologists are predicting another possible La Nina event by the end of the year, which could bring more heavy rain and extreme weather.

If the weather phenomena does occur for what would be the third year in a row, it would be a "triple dip", an occurrence which has only happened twice since the 1950s.

"We are in a La Nina watch," meteorologist Shane Kennedy said.

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"Which is a 50 per cent chance of seeing La Nina develop in the spring or summer."

A La Nina event is a complex weather pattern that sees warmer water pushed towards Australia and Asia, resulting in more water evaporation, more rain and a higher chance of cyclones in summer.

Experts say triple dips are so rare it's difficult to predict if a third La Nina would be weaker or stronger than in the past two years.

Farmer Justin Vanstone, who grows broccolini, cabbage and lettuce in Queensland's Lockyer Valley, said the threat of another extreme weather event is putting farmers on edge.

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He said his crop was destroyed by torrential rains this year with the chance of more rain in spring threatening to hinder yet another harvesting season.

"We had 100 per cent losses of one week before ready to harvest, beautiful looking crops and 100 per cent loss in some crops," Vanstone said.

"I'd say there's a lot of businesses that are right on their limits.

"And that's where there's probably more nervousness as we said about the rain forecast this weekend."