Climate of Halls Creek

Halls Creek has a tropical semi-arid climate with very hot summers and warm dry winters. There are two distinct seasons; the "wet", usually from December to March and characterised by high temperatures and the occasional rain event, and the "dry" for the remainder of the year. The mean annual rainfall is 555mm on an average of 60 days, although there is considerable variation from year to year.

The main broadscale influences are the band of high pressure known as the sub-tropical ridge well to the south and the low pressure trough which develops over the Kimberley during the hotter months. These combine to produce a general southeast to easterly wind regime for much of the year but westerly winds are common near the coasts during the hotter months.

Over 80% of the average annual rainfall occurs between December and March and is associated with thunderstorms and tropical lows or cyclones. These systems can produce heavy rain over short periods and often a significant proportion of the yearly total can fall in just one or two days. The unreliable nature of the occurrence and movement of thunderstorms and tropical systems results in the annual rainfall being highly variable.

From May to October, days are characteristically clear and sunny. The infrequent rain during the drier months is usually associated with cloud bands originating over tropical waters to the northwest.

While tropical cyclones can threaten the Kimberley coasts with storm force winds and high seas they weaken as they move inland. Halls Creek is far enough inland for the major effect to be heavy rainfall. The highest daily rainfall occurred on 9 January 1959 when a cyclone produced 202.2 mm. The highest annual total is 1039 mm in 1993 due mainly to heavy February rains associated with two tropical lows.

It is not uncommon for very little rain to occur for many months. The median rainfall for the months of June to September is zero. Long periods of below average rainfall are associated with the failure of the wet season. Dry periods last century include 1905, 1931, 1936, 1945-46, 1951-52, 1963-65 and 1992.

From October to January maximum temperatures average over 36°C. The highest temperature recorded is 45.0°C on 8 November 1988. By contrast winters are mild to warm with the July average maximum and minimum temperatures being 27.1°C and 12.5°C respectively. Overnight temperatures rarely fall below 5.0°C and only fall below 10°C about once a week during June and July. The lowest temperature recorded is 0.2°C on 18 July 1945.

The average relative humidity varies from 22-57% at 9am and from 16-40% at 3pm with the higher values occurring in the wetter December to March period. Evaporation is high and varies from an average of 11.3 mm per day in November to 6.1 in June.