Lumen Sites for mine & construction sites

Central West NSW and Cobar weather for site work

The Central West of New South Wales mixes copper, gold and coal. Cadia East is near Orange and Northparkes near Parkes, with Cowal further west and Tomingley south-west of Dubbo; the base metals mines around Cobar include Peak Mines, Endeavor and Tritton; and coal comes from Springvale and Clarence near Lithgow and from Moolarben, Wilpinjong and Ulan near Mudgee. The weather changes with height: the tablelands around Orange, Bathurst and Lithgow have mild summers and frosty winters, while the plains out to Parkes, Dubbo and Cobar are hot in summer.

The year at a glance

On the tablelands, January highs average 26–30° and July nights 1–2°. West of the ranges it is hotter and drier: Parkes and Dubbo average 34° in January and Cobar 36°, and Cobar gets 383 mm of rain a year, against 830–857 mm at Lithgow and Orange. Rain is spread through the year, with a little more from late spring into summer, and November is the wettest month in most towns.

Averages for 1995–2024 from SILO (Queensland Government, CC BY 4.0), interpolated from Bureau of Meteorology observations. Heat-stress days: estimated WBGT reaching 28°, the caution level Lumen Sites starts with. Select a town for its month-by-month figures.
Town	January high	July low	Rain a year (mm)	Wettest month	Days reaching 40°	Heat-stress days
Orange	28°	1°	857	Nov 85 mm	0	12
Bathurst	30°	1°	647	Nov 79 mm	under 1	30
Lithgow	26°	2°	830	Jan 101 mm	0	9
Mudgee	31°	2°	722	Nov 81 mm	1	51
Parkes	34°	3°	612	Nov 74 mm	5	64
Dubbo	34°	3°	616	Dec 66 mm	5	74
Cobar	36°	4°	383	Nov 44 mm	11	75

Heat and heat stress

Heat-stress days by month

Average heat-stress days a month, 1995–2024: days when the estimated wet bulb globe temperature (WBGT) at the day’s peak reaches 28°, the caution level Lumen Sites starts with. From SILO (Queensland Government, CC BY 4.0), interpolated from Bureau of Meteorology observations.
Town	Jan	Feb	Mar	Apr	Sep	Oct	Nov	Dec
Orange	7	3	<1	0	0	0	<1	2
Bathurst	13	7	2	0	0	0	2	6
Lithgow	5	3	<1	0	0	0	1	2
Mudgee	17	12	6	<1	0	<1	4	11
Parkes	21	16	8	<1	0	1	5	13
Dubbo	22	17	10	1	0	1	8	15
Cobar	22	18	10	1	<1	2	8	15

Heat stress rises quickly as you head west and down off the ranges. Lithgow averages 9 heat-stress days a year and Orange 12, but Mudgee has 51, Parkes 64, Dubbo 74 and Cobar 75, with 11–16 of them at the stop level from Parkes west. Cobar reaches 35° on 55 days a year and 40° on 11. On the plains, December to February brings most of the heat stress, and the caution level is reached on about two in three January days.

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. The WBGT calculator and heat stress forecasts cover the details.

Storms and lightning

Thunderstorms are most frequent from spring to early autumn across inland New South Wales, and some bring large hail, damaging wind gusts and flash flooding. Storms often build through the afternoon, and lightning can strike well away from the rain, so sites rely on detection rather than thunder: see lightning stand-down alerts.

Frost, fog and snow

Tableland winters are cold. July days reach only 10–13° at Orange, Lithgow and Bathurst, nights average 1–2°, and frost is common from late autumn into spring. Fog settles in the valleys on still winter mornings and can be slow to lift, delaying early starts, lifts and traffic. Snow falls on the highest ground, around Orange and Lithgow, in some winters, and black ice can form on the roads. Those clear, still nights also set up temperature inversions that hold blast fumes and dust close to the ground: see blasting and temperature inversions.

Rain and floods

Long wet spells, as in La Niña years, flood the Macquarie and Lachlan rivers and their tributaries and cut roads across the region, and heavy storms can flood creeks and low crossings within hours. Cobar is dry by comparison, with rain on about 45 days a year against 87–99 on the tablelands at Orange and Lithgow. More in rain, the wet season and haul roads.

Planning a year on site

West of the ranges, put shutdowns and heavy outdoor work into April to October, when heat stress is rare.
Plan for heat stress on the plains from November to March, and most of all from December to February.
On the tablelands, allow for frost, fog and icy roads on winter mornings.
Have the lightning plan and shelters ready by October, before the storm season.
After long wet spells, check river crossings and access roads before sending crews out.