The chance of an El Nino forming during the second half of 2018 is increasing as the equatorial Pacific Ocean continues to warm.

The Bureau of Meteorology monitors oceanic and atmospheric conditions in the Pacific Ocean and issues fortnightly statements regarding the El Nino Southern Oscillation (ENSO) cycle. This cycle has three phases: Neutral, El Nino and La Nina.

The Pacific Ocean is currently in a neutral phase, although sea surface temperatures near the equator have warmed in recent weeks. This warming has started to extend below the surface, which can indicate the early stages of El Nino.

In their latest fortnightly ENSO statement, which was released on Tuesday, the Bureau increased the chance of El Nino developing later in the year to 50 per cent.

Neural ENSO conditions - neither El Nino or La Nina - are expected to persist in the Pacific Ocean during the rest of winter. However, five of the eight climate models surveyed by the Bureau now predict that El Nino thresholds could be exceeded during the Australian spring.

El Nino events can cause below average rainfall across parts of northern and eastern Australia during winter and spring, although they tend to have less of an influence on rainfall during summer. An El Nino even starting during spring is a bit later that usual, as they typically start and end in autumn.

Visit http://www.bom.gov.au/climate/enso/ for the latest information on ENSO from the Bureau of Meteorology.