Lumen Sites for mine & construction sites

Northern Territory weather for site work

Mining in the Northern Territory runs from the Top End, with manganese on Groote Eylandt, bauxite at Gove and the former Ranger uranium mine near Jabiru, to the gold country around Tennant Creek. The two halves have very different weather: a tropical wet and dry in the Top End, and desert heat with cold winter nights in Central Australia.

The Top End: wet and dry

In Darwin, 81% of the year’s 1,750 mm or so falls from December to March, while June to August average just 1–2 mm a month. Katherine is drier and hotter, with about 1,060 mm a year and October highs averaging 38°. Gove and Groote Eylandt stay wet for longer: March is their wettest month, and April is still wet.

The build-up, from October to December, is the hardest time to work outside. The heat peaks before the rain arrives and the humidity climbs. Unsealed roads across the Top End can close for long stretches of the wet, so access, supplies and crew changes need planning months ahead.

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
Darwin	32°	19°	1746	Jan 478 mm	0	327
Palmerston	32°	18°	1824	Jan 488 mm	0	329
Katherine	34°	14°	1061	Jan 264 mm	11	296
Nhulunbuy	32°	21°	1420	Mar 304 mm	0	340
Jabiru	34°	19°	1527	Jan 368 mm	4	333
Alyangula	33°	17°	1307	Mar 292 mm	0	324
Tennant Creek	37°	12°	512	Jan 138 mm	24	170
Alice Springs	37°	4°	298	Jan 59 mm	18	98

Heat stress all year

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	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Darwin	31	28	31	30	26	18	19	24	29	31	30	31
Palmerston	31	28	31	30	26	18	20	24	29	31	30	31
Katherine	31	28	31	28	21	12	11	17	27	30	30	31
Nhulunbuy	31	28	31	30	29	23	22	24	29	31	30	31
Jabiru	31	28	31	30	27	20	21	24	29	31	30	31
Alyangula	31	28	31	30	27	18	18	21	28	31	30	31
Tennant Creek	30	26	24	10	2	1	1	1	7	17	23	28
Alice Springs	24	20	13	2	<1	0	0	0	1	6	13	20

By the Bureau of Meteorology’s simplified formula, Darwin reaches the caution level of 28° WBGT on 327 days a year and the stop level of 32° on 253. The formula assumes moderate sun and light wind, so cloud and sea breezes can make conditions easier than it suggests, but the point holds: in the Top End, heat has to be managed all year, not just in summer. The WBGT calculator shows how much the humidity adds.

Storms, lightning and cyclones

The Top End has some of the most frequent thunderstorms in Australia, mostly in the build-up and the wet season, so lightning stand-downs are routine: see lightning stand-down alerts. The coast is exposed to tropical cyclones from November to April, and Cyclone Tracy destroyed much of Darwin on Christmas Day 1974. See cyclone season for remote sites.

Central Australia

Tennant Creek and Alice Springs are hot in summer and dry for most of the year. Tennant Creek averages 139 days a year reaching 35°, and 78% of its 510 mm of rain falls from December to March. Alice Springs averages 101 days reaching 35° and only about 300 mm of rain, and its winter nights are cold: July lows average 4°, with frost on clear nights. Those clear, cold nights also set up strong temperature inversions, so morning blasts need care: see blasting and temperature inversions.

Planning a year on site

In the Top End, put shutdowns, earthworks and big lifts into the dry season, May to September.
Plan wet-season access early: roads, barges, airstrips and crew changes.
Run heat stress plans all year in the Top End, and from October to March in the centre.
Rely on lightning detection, not thunder, through the build-up and the wet.