Tropical Climate Update

2015-16 Australian northern wet season review

Many parts of northern Australia (i.e. areas north of latitude 26° South) experienced drier-than-average conditions during the northern wet season which concluded 30 April. The northern tropics, including the Northern Territory’s Top End, far northern Western Australia, Cape York Peninsula and the Torres Strait Islands in Queensland had significantly below-average rainfall during the October to April period. Apart from one substantial active monsoon period in the second half of December, the season was characterised by infrequent and weak monsoonal activity. Rainfall totals across northern regions were generally 20 to 40 per cent below average.

Northern Australia also experienced record heat during the wet season. Averaged over northern Australia, mean and overnight temperatures were warmest on record, while daytime temperatures were second warmest. The heat was particularly pronounced north of 20° South during the January to April period, with daytime and overnight temperatures all highest on record.

Tropical cyclone activity was significantly below average, with only three tropical cyclones – Stan, Uriah and Tatiana – observed in the Australian region. Of the three cyclones, only Stan made a coastal crossing: east of Port Hedland as a category 2 system late in January. Tropical cyclone Winston, which affected the Queensland coast during February, had weakened to below tropical cyclone intensity prior to entering the Australian region. The average number of tropical cyclones observed during a season is eleven, and the previous all-time low was five.

Madden–Julian Oscillation strengthens in western hemisphere

The Madden–Julian Oscillation (MJO) has been weak since the beginning of April. It has recently strengthened and moved into the western hemisphere. Some models forecast a moderate MJO over the Indian Ocean in the coming week. When the MJO moves over the Indian Ocean at this time of the year, rainfall is typically near-average over northern Australia, while daytime temperatures are typically higher than normal.

See the Bureau's MJO Monitoring for current MJO information.

El Niño a major factor in the 2015-16 northern wet season

El Niño typically brings warmer and drier conditions to much of northern Australia, particularly during the January to April period - as was experienced across northern Australia during the most recent wet season. El Niño also typically reduces tropical cyclone activity in the Australian region. The previous record low seasons when only 5 tropical cyclones were observed - 1987-88 and 2006-07 - were both El Niño years.

The current El Niño is now in its last stages, with 50% likelihood of La Niña forming later in 2016 – about double the normal chance. La Niña is often, but not always, associated with above-average winter-spring rainfall over northern, central and eastern Australia.

See the Bureau of Meteorology's ENSO Wrap-Up for official El Niño information.