100 Years of Australian Rainfall

100 years of Australian rainfall: the long-term patterns

Australia's reliable national rainfall series starts in 1900, giving more than a century of context. A century-long national average is not a local water-supply forecast: large wet years can mask drying in individual regions. Compare like-for-like seasonal observations and a clearly stated reference period before drawing conclusions about long-term weather trends.

• South-western Australia: April–October rainfall since 1970 is about 16% lower than the 1900–1969 average. May–July rainfall is about 20% lower over the same comparison.
• South-eastern Australia: April–October rainfall during 1994–2023 is about 9% lower than in 1900–1993. Even after the Millennium Drought, the 2010–2023 average remained about 5% below the earlier baseline.
• Northern Australia: October–April wet-season rainfall since 1994 is about 20% above the 1900–1993 average, in the 2024 assessment. The increase is particularly evident in the north-west; it is not uniform across all Queensland locations.

These are different regional and seasonal comparisons, not three directly comparable century-long rates. BOM and CSIRO explain the periods and regional boundaries; BOM's trend guidance explains why choosing a different start year can change a fitted trend.

Why the rain changes from year to year

El Niño–Southern Oscillation, the Indian Ocean Dipole and the Southern Annular Mode influence Australia's rainfall, alongside individual weather systems. La Niña often favours wetter conditions in the east, but it does not guarantee flooding everywhere; El Niño is not a guarantee of drought at every station.

Southern drying is associated with changes in circulation, including more high-pressure systems and fewer rain-producing lows and fronts. Learn how these influences work in our El Niño and La Niña guide and Indian Ocean Dipole guide.

Historical rainfall by state and territory

A state boundary is not a climate boundary. Northern wet-season rain, east-coast storms, southern cold fronts and inland episodic rain create very different histories within the same state. The following summaries describe regional context rather than invented state-wide percentage changes; use BOM's regional series for a particular place and period.

Queensland

Queensland spans tropical wet-season climates, a comparatively dry interior and a subtropical east coast. Its history includes intense cyclone and monsoon rainfall as well as prolonged drought. The northern wet-season increase does not apply evenly across the state: the 2024 assessment also identifies lower rainfall trends in parts of eastern Queensland south of the tropics.

Crohamhurst and Bellenden Ker feature prominently in point-rainfall records, while 2019 drought and the 2022 south-east floods demonstrate contrasting hazards. Compare present conditions on the Queensland weather page.

New South Wales

NSW's coast, ranges and western plains have distinct rainfall histories. Eastern coastal rain can be concentrated into intense multi-day events, while inland farming regions are vulnerable to sustained rainfall deficiencies. The 2019 climate statement describes particularly severe drought in NSW; the 2022 floods show why a dry period does not remove future flood risk.

Southern parts of NSW fall within the south-eastern cool-season drying region, but that finding should not be extended to the entire state. See NSW weather and forecasts.

Victoria

Victoria lies within the broad south-eastern rainfall context, where dependable cool-season rainfall matters for agriculture, catchment runoff and water storage. The Millennium Drought affected the region during 1997–2009, and cool-season drying continued beyond it. Mountain, coastal and inland observations should still be assessed separately rather than treated as one identical local trend.

Our Victoria weather page covers current conditions, which are separate from this historical climate assessment.

Western Australia

WA provides one of the clearest examples of opposing regional histories. South-western April–October rainfall has declined markedly relative to the pre-1970 baseline, whereas the tropical north-west participates in the increased northern wet-season rainfall described in the 2024 assessment. A single state average can conceal both changes.

Season and location are especially important when comparing Perth and the South West with the Kimberley, Pilbara or interior. Visit Western Australia weather for today's outlook.

South Australia

South Australia's wetter southern districts and dry inland areas respond differently to rain-producing systems. Cool-season changes across southern Australia affect the timing and reliability of rainfall, while isolated heavy events can still deliver large totals inland. Motpena's listed daily extreme is a reminder that an arid climate does not eliminate intense-rain risk.

Do not apply the south-western WA percentage to SA. Use a local station or matching regional series alongside South Australia forecasts.

Tasmania

Tasmanian rainfall needs to be interpreted by location, terrain and season rather than as a single island-wide trend. The 2024 assessment identifies below-average warm-season rainfall in parts of Tasmania in recent decades, and substantial streamflow declines at many reference gauges. Rainfall and streamflow are related, but they are not interchangeable measurements.

Use Tasmania weather and the relevant station history for local comparisons.

Northern Territory

The Top End's wet-season rainfall and the arid centre's episodic rain tell different stories. The Territory lies within the northern region used in the 2024 wet-season assessment, but a regional average is not a guarantee of wetter conditions each year. Very dry seasons and exceptionally heavy daily rain can occur within a broader wetting pattern.

For current conditions across the Territory, see Northern Territory weather.

Australian Capital Territory

The ACT is part of the south-eastern Australian climate context, and local rainfall varies with terrain and individual weather systems. BOM's NSW area-average rainfall series includes the ACT; it is not a separate Canberra station record. Use Canberra-area station observations for local historical totals rather than assigning the NSW average to the ACT.

Check ACT weather for current forecasts.

Extreme rainfall records, droughts and flood years

Extreme rainfall records describe a measured amount at a station over a specified duration. They do not represent an entire state's rainfall or automatically establish a flood's severity. Keep daily, monthly, annual and area-averaged totals separate; a mountain-top gauge and a national annual average answer fundamentally different questions.

Highest daily rainfall listed for each state and the NT

The figures below reproduce the BOM national climate-extremes table, whose stated data cutoff is 31 December 2021. They are historical listed records, not a live verification of records through 2026. The table does not supply a separate ACT daily record.

Two records above predate 1900. They are retained for context and are not part of a pre-1900 continent-wide rainfall comparison. The same BOM table lists 12,461 mm at Bellenden Ker (Top Station), Queensland, in 2000 as the highest annual station total in Australia.

From the Millennium Drought to recent wet years

• 1997–2009: the Millennium Drought strongly affected south-eastern rainfall and water availability. It is a multi-year climate episode, not a single station record.
• 2010–2011: major eastern Australian flood years associated with La Niña illustrate how wet conditions can return after drought. Not every catchment or state shares the same annual total.
• 2019: BOM reported a national area-average of 277.6 mm, 40% below the 1961–1990 average of 465.2 mm, and identified it as the driest year in the national record in its 2019 annual statement.
• 22 February–9 March 2022: extreme multi-day rainfall affected south-east Queensland and eastern NSW. BOM's Special Climate Statement 76 documents the event, including several locations receiving more than one metre of rainfall.

The 2024 climate assessment identifies 1974, 2010–2011 and 2021–2022 among significant eastern flood years associated with strong La Niña events. Significant floods can also happen without La Niña.

Less dependable rain can coexist with heavier downpours

BOM and CSIRO report increasing intensity of heavy rainfall, including short-duration extremes, even as some regions receive less cool-season rain overall. Flood risk also depends on antecedent soil moisture, catchment size, river regulation, land use and, near the coast, tides and sea level.

A climate trend alone cannot tell you whether a road or property will flood. Read our Australian flooding guide and check current BOM weather warnings; never drive through floodwater.

How to find and compare historical rainfall data

Start with the scale of your question. Use an area-average series for a national or state comparison, a station record for a town or property, and a trend map for spatial patterns. A forecast map is not a historical observation, and a missing station value must not be treated as zero rainfall.

1. Choose a source: BOM rainfall time series for regional comparisons, or BOM Climate Data Online for individual stations.
2. Choose the same duration: calendar-year rainfall, an October–April wet season and an April–October cool season are different measurements.
3. State the baseline: an anomaly is a difference from a reference average, often 1961–1990 in the sources used here. A decile ranks a total against the historical distribution; it is not a percentage change.
4. Check completeness: station moves, observation gaps and quality-control updates can affect local comparisons. Older regional coverage is not equally dense everywhere.
5. Separate the past from the outlook: pair this guide with recent observed rainfall, the daily rainfall forecast and the Australian seasonal forecast.

For farming or water-supply planning, consider rainfall timing and reliability, not just the annual mean. Historical station records, seasonal outlooks and current warnings provide complementary information, but none removes the uncertainty of a specific future event.

Sources, attribution and limitations

This independent guide attributes observation and climate findings to the Bureau of Meteorology and CSIRO. It is not affiliated with the Australian Government. The main synthesis is State of the Climate 2024; historical statements and the extremes table retain their original dates and cutoffs rather than implying complete 2026 data.

• BOM–CSIRO State of the Climate 2024: rainfall, heavy rainfall and streamflow
• BOM rainfall time-series methods, regional coverage and reference periods
• BOM rainfall trend-map interpretation
• BOM Australian climate-extremes table (PDF; data through 2021)
• BOM Annual Climate Statement 2019
• BOM Special Climate Statement 76: February–March 2022 rainfall and floods (PDF)