Olympic Dam and Far North SA weather for site work

South Australia’s far north is desert mining country. Olympic Dam sits beside Roxby Downs, Carrapateena lies to the south-east, and Prominent Hill and the Peculiar Knob iron ore mine are south-east of Coober Pedy, which with Andamooka is also opal country. Leigh Creek is in the northern Flinders Ranges. Further south, Whyalla, with the iron ore mines of the Middleback Ranges, and Port Pirie, with its smelter, sit on Spencer Gulf. Summers are long and very hot, rain is scarce and unreliable, and winter nights are cold.

The year at a glance

In the far north, January highs average 36–37° and July nights 5–6°. Rain is low and spread through the year, 157–208 mm, and falls on only 23–28 days a year with 1 mm or more: no month averages more than 21 mm at Roxby Downs, Andamooka or Coober Pedy. Winter days are mild, 17–19° in July, but clear nights are cold and can bring frost. Spencer Gulf is milder and a little wetter: Whyalla’s January high is 31° and Port Pirie’s 33°, and their 270–333 mm a year peaks in June, as Adelaide’s does.

Heat and heat stress

The far north is hot and dry. Coober Pedy reaches 35° on 81 days a year and 40° on 25, and Roxby Downs reaches 35° on 74. The dry air keeps the estimated WBGT lower than the temperature suggests, but Roxby Downs still averages 81 heat-stress days and Andamooka 84, about three times Adelaide’s 27. Nearly all of them fall between November and March, and most in December to February.

These figures use the Bureau of Meteorology’s simplified formula, which assumes moderate sun and light wind, so read them as how often heat needs managing. Crews arriving from Adelaide, where January averages 30°, step into 36–37° days, so the first days of a summer swing need extra care. The WBGT calculator and heat stress forecasts cover the details.

Storms, dust and wind

Thunderstorms are less frequent here than in northern Australia and most likely from late spring to early autumn. Many bring little rain but plenty of lightning and strong outflow gusts that raise dust. Hot northerly winds ahead of cold fronts raise dust too, and the southerly change behind a front can drop the temperature sharply and swing the wind around. Lightning can strike well away from the storm that produced it, so sites rely on detection rather than thunder or rain: see lightning stand-down alerts.

Rain and floods

Rain is unreliable. Many months bring almost nothing, then a band of tropical moisture or a decaying tropical low from the north can drop more than a month’s average in a day or two, usually in summer. Creeks that are dry most of the year run fast, unsealed roads close, and even sealed highways can be cut for days. On Spencer Gulf, rain falls on 45–53 days a year, most often in winter, when cold fronts bring showers and strong winds. More in rain, the wet season and haul roads.

Planning a year on site

• Put shutdowns and heavy outdoor work into May to September, when heat stress is almost unknown and days are mild.
• Manage heat from November to March, when nearly all heat-stress days fall, and most of all in December to February.
• Plan water, shade and cool rest areas for long hot spells, with extra care for crews new to the heat.
• After heavy rain, check access roads and creek crossings before sending crews out.
• Clear, still winter nights set up temperature inversions, so time blasts for after they break: see blasting and temperature inversions.

Related: South Australia forecasts · Goldfields and Murchison weather for site work · Blasting and temperature inversions · Lightning distance calculator