Seasonal climate summary southern hemisphere (spring 2013): Warmest Australian spring on record

Abstract

Southern hemisphere circulation patterns and associated anomalies for austral winter 2013 are reviewed, with an emphasis on Pacific Basin climate indicators and Australian rainfall and temperatures. El Niño–Southern Oscillation (ENSO) conditions remained neutral throughout winter 2013 though some ENSO indicators, such as the SOI, surpassed La Niña thresholds at times during the season. Sea surface temperature patterns across the equatorial Pacific Ocean displayed a weak La Niña-like signal, but did not reach La Niña thresholds. A negative Indian Ocean Dipole event contributed to above average rainfall across southern and northwestern Australia, before weakening in early August, whilst a strongly negative phase of the Southern Annular Mode (SAM) contributed to above-average rainfall across southern areas in August. Above average rainfall saw an easing of rainfall deficiencies in the southeast, but a lack of winter rainfall saw a worsening of deficiencies in inland Queensland and northern New South Wales. Averaged across Australia, winter maxima were second warmest on record, and minima were sixth warmest on record. Overall, Australia’s mean winter temperature was 1.29 °C above average: the third highest on record. An unusual period of warmth which started in the last week of winter also saw Australia record its warmest winter day on 31 August.