All of the Bureau of Meteorology's eight international models it uses now predict an El Nino event by the end of spring, dimming hopes of quenching rains that would aid farmers and ease the bushfire risks.

The Bureau of Meteorology's latest El Nino-Southern Oscillation update shifts the odds slightly from a fortnight ago when only a majority of the models had forecast an El Nino by spring's end.

Robyn Duell, a senior bureau climatologist, cautioned that model forecasts had picked an El Nino at this time in 2014, only for the drivers - namely a relative warming in the eastern tropical Pacific compared with the west - to back off.

"We need to see the [easterly] trade winds weakening - that's the key we're looking for," Ms Duell said. "Models are not enough."

Still, the Southern Oscillation index - which gauges pressure differences between Darwin and Tahiti - had recently become more "El Nino-like" the bureau said.