Climate outlook for May to July
Issued 26 April 2018
Climate outlook overview
- The May to July rainfall outlook, issued 26 April 2018, indicates below average rainfall is likely for parts of southwest Australia and western Victoria, but for much of the country there is little shift towards a wetter or drier than average period.
- May to July daytime temperatures are likely to be warmer than average for southern Australia and the northern Kimberley in WA.
- Night-time temperatures are likely to be warmer than average for large parts of southern Australia and the northern Kimberley while eastern Queensland is likely to have cooler than average nights.
- May days and nights are very likely to be warmer than average for much of the country.
- The El Niño–Southern Oscillation (ENSO) in the tropical Pacific Ocean is neutral—neither El Niño nor La Niña—and is expected to remain neutral through the coming season. The Indian Ocean Dipole (IOD) is also neutral, with the possibility of a negative IOD event forming during winter. With mostly neutral climate drivers, there is no strong push towards broadscale wetter or drier conditions across the country. See the Climate Influences section for more information, or our blog on what to expect when climate drivers are neutral or weak.
Drier three months likely in southwest Australia
- Southwest Australia and parts of western Victoria have an increased chance of a drier than average May to July. In contrast, a wetter than average season is likely for far eastern Victoria and eastern Tasmania. Parts of northern Australia are also likely to be wetter, however, rainfall during the start of the northern Australian dry season (May-September) is typically low, meaning little rainfall is needed to exceed the median. Elsewhere, the chances of a wetter or drier season are roughly equal.
- Historical outlook accuracy for May to July rainfall is moderate over western and southern WA, the southern NT, southeast SA and the eastern States. See map for more detail.
Chances of a warmer May increase nation-wide
- May days and nights are very likely to be warmer for much of the country. For daytime temperatures, chances are highest (greater than 80%) across northern and eastern parts of the country.
- May to July daytime temperatures are likely to be warmer than average for southern Australia, including southwest WA, southeast NSW, Victoria and Tasmania. Chances are highest (greater than 80%) in Tasmania.
- Night-time temperatures are likely to be warmer than average for southern Australia (except the southwest) while eastern Queensland is likely to have cooler than average nights.
- Historical accuracy for maximum temperatures is moderate to high over most of Australia for May to July. Minimum temperature accuracy is also moderate to high for most of Australia, except parts of southeast mainland Australia where accuracy is moderate to low.
Climate influences
- Neutral El Niño–Southern Oscillation (ENSO) conditions prevail in the tropical Pacific Ocean. A neutral ENSO state is forecast to persist through the forecast period.
- The Indian Ocean Dipole (IOD) is also neutral. Three of six climate models, including the Bureau's model, suggest an increased likelihood of a negative IOD event developing during winter. A negative IOD typically results in a wetter than average winter-spring for southern Australia. However, forecast accuracy for the IOD is lower during the autumn compared to other times of the year, and should be viewed with some caution.
- With mostly neutral climate drivers, there is no strong shift in the outlook towards widespread wetter or drier conditions across most of Australia. This does not indicate average rainfall and temperature for Australia. Rather, it means a reduced chance of prolonged or widespread very wet, dry, hot, or cold conditions. Read more in our recent blog on neutral climate drivers and outlooks. Other climate drivers, such as local sea surface conditions or soil moisture, may also have greater influence over the coming months.
- Above average sea surface temperatures in the Tasman Sea, associated with lower pressures over eastern Australia, may be increasing the chance of easterly (onshore) winds bringing above average rainfall in the far southeast of the country. Likewise, this pattern may also reduce the strength of the westerly winds that would typically bring moisture into other parts of southern Australia.
- In addition to the natural drivers such as the El Niño–Southern Oscillation and the Indian Ocean Dipole, Australian climate patterns are being influenced by the long-term increasing trend in global air and ocean temperatures.
- Bureau climatologists continually monitor the climate for any significant developments, with information on El Niño/La Niña and IOD events available fortnightly via the ENSO Wrap-Up. For a summary of Pacific and Indian Ocean outlooks, please see the Climate Model Summary.
