Fifty Years of Rainfall at Tom Cullity Drive

This winter marks twenty-one years since Martin Black and I planted our Chardonnay block at 448 Tom Cullity Drive. On that day the soil was firm, the air was still, and the vines went into the ground without fuss. A photograph was taken of me that morning as I planted a Gin Gin clone rootling into the soil. Yesterday I returned to the same spot for a second photograph with the same vine. (See pic. below) Two decades on, the structure is strong and settled, the cordons are firmly set in place, their roots reaching down to the summer water table below. What struck me most yesterday was not the vine itself but the condition of the soil around it. The ground was saturated, water sitting between the posts, the rows heavy underfoot even on a dry day. The two photographs show the same vine exactly twenty-one years apart, but the saturation of the ground could not be more different.

It has become a common observation across the region this winter. Vineyards are soddened, paddocks have held water for weeks, and creeks have spilled their banks. Some vineyards have even found themselves underwater for the first time. From Yallingup to Witchcliffe, people have been saying the same thing: no one can remember a winter quite like it.

Directly opposite our Chardonnay vineyard on Tom Cullity Drive sits an official rainfall gauge, maintained by the Department of Water and Environmental Regulation and known as Wilyabrup Brook Site 509191. It has been measuring rainfall since 1973. A few years are missing in the early 2000s when monitoring was suspended, but the archive is otherwise continuous for more than four decades. By any statistical measure, it is a rare resource. To mark the twenty-first anniversary of plating that vineyard, I thought it would be a good moment to turn to the record and see what the last fifty years have to say.

The figures for 2025 stand out immediately. June brought 305.4 millimetres, the third-wettest June on record at the site, behind 1974 at 324.0 millimetres and 1998 at 311.3. Then came July with 348.0 millimetres, the wettest single month in the entire half-century record. By themselves those two months delivered more than 650 millimetres. August then added 177.8 millimetres, bringing the three-month winter total for the Tom Cullity Drive gauge to 831.2 millimetres.

To set the record in its full historical context, the Cowaramup gauge allows us to extend the picture back to 1967, the year Tom Cullity planted the first vines at Vasse Felix further up the street. That winter recorded 803 millimetres, making it the second wettest winter in the entire viticultural era of Margaret River. For nearly six decades it held the record, the wettest winter since vines were planted. In 2025 that record has finally been surpassed. With 831.2 millimetres to the end of August, this winter now stands alone at the top of the ledger as the wettest winter since vines were planted in Margaret River.

The archive also reminds us that the story of rain here has always been one of contrasts. The wettest year at Tom Cullity Drive overall remains 1974, when the total reached 1,304 millimetres. The driest complete year came in 1987, with just 780. Within those brackets lie extraordinary variations. The driest July on record was 2012, with only 75.41 millimetres, while the wettest was this year, at 348. August has ranged from a high of 227.4 millimetres in 2018 to a low of 61.08 in 1978. September has reached as high as 193 in 1978 and fallen as low as 33.8 in 2018. Even October has swung from 136 in 1989 to only 18 in 1983. Summer is equally capable of surprises. January 1981 delivered no measurable rain at all, and February that year reached only 1.77 millimetres. February 1993 was completely dry, while February 1994 recorded 9.27. February 2018 fell under one millimetre, and in 2023 January brought 1.0 and February 0.6. At the other end of the scale, January 2016 brought 100.2 millimetres in a single month, a genuine midsummer soaking that transformed the season. These figures show that rainfall at Tom Cullity Drive has never been steady. Extremes are built into the system.

When you step back and look at the decades, the picture is not straight forward. The 1970s averaged close to 1,000 millimetres a year, the 1980s sat a little lower, and the 1990s lifted again, averaging just above that line. Then came the 2010s, and the drop was unmistakable. Across that decade the site averaged only about 880 to 900 millimetres. It was a decline of roughly eighty to one hundred millimetres compared with the early decades, and for many it looked like proof of the drying trend that has been widely reported across the South West.

But the 2020s so far have complicated the story. In just five seasons this decade the gauge has already captured 1,203 millimetres in 2021, 943 in 2022, 821 in 2023, 967 in 2024, and 1,004.6 by the end of August this year. Taken together, those figures put the decade’s running average close to 1,000 millimetres again. On the surface it looks as though the decline has stopped, or perhaps even reversed.

So what is going on. Has rainfall here levelled out. Is Margaret River entering a new phase. Or are we simply seeing the natural variability of the system producing another run of wetter years.

The evidence suggests the latter. The broader government datasets, covering the entire South West, do confirm a real decline: rainfall since the 1970s has dropped by around 15 per cent. What the Tom Cullity Drive record shows is that the signal is not smooth. It is interrupted by spikes of abundance. Years such as 1996, 2016, 2021 and now 2025 sit far above the line. They do not erase the drying trend, but they mask it in the short term. That is the essence of climate variability here, the averages point down, but the extremes still surge up.

The lesson from fifty years of data is that the climate in Wilyabrup has two defining qualities: variability and unpredictability. Extremes are the rule, not the exception. Strong winters build the annual total, but even those winters can range by hundreds of millimetres from one year to the next. Spring and summer can up the balance, but they cannot make up for a poor June and July. That is why the shape of the 2025 season is so decisive.

The question now is whether this year could also break the annual record for Wilyabrup set in 1974. With 1,004.6 millimetres already recorded by 31 August, another about 299 would be needed before December 31st to pass the mark of 1,304. On average the last four months provide about 205, though in 1983 more than 400 millimetres fell between September and December. So it is not impossible. But the odds are against it. A final figure somewhere between 1,100 and 1,200 millimetres is more likely, enough to place 2025 among the great wet years, but still shy of the absolute peak.

One thing, however, is already certain. The figures are in, the comparisons are clear, and the record has been set. By the end of August 2025, the winter total stood at 831.2 millimetres, surpassing the 803 millimetres of 1967. That makes 2025, unequivocally, the wettest winter in Wilyabrup since vines were first planted in 1967.