Været i Margaret River i september

Regulars are specific this falls within one of the two best windows of the year here, late March into early April, rarely bringing more than a brief shower and mild enough for comfortable beach walking. Our row backs that mild, genuinely dry read, 21.8C over 10.7C nights feeling 9C, with rain light at 56.7mm across 8.2 days and humidity at 69 percent. Regulars are consistent the day-to-night swing runs genuinely wide, sunny 20-plus-degree afternoons giving way to nights that can drop below 10C, a light jacket or fleece worth having for most of the day regardless of how warm it starts. The sea sits at 20.7C. The record: 8.9 hours of sun, a 17.8 kph wind and AQI 23.

November is the window regulars point wine-tourers toward: warm enough for the vineyards without the summer school-holiday crowds that arrive from December. Our row backs a genuinely pleasant spring, 21.9C over 10.3C, with only 32mm across 5.1 days and one of the cleanest air columns in this project at AQI 23. The wind is real at 19.5 kph, and they note it runs stronger still down at Augusta on the Southern Ocean edge of the region than in the wine country proper - worth choosing where you stay for that reason alone. Early November also catches the tail of spring wildflowers. The sea sits at 19.4C, a look-more-than-swim proposition on this coast even in late spring. The record: humidity 66 percent, 11.7 hours of sun.

March is the end of the Western Australian summer, still hot and dry, and regulars are honest that the vineyards are past their best - the picking is generally done and the vines are beginning to lose their leaves, so this is not the month for the lush green photographs. Exactly when the grapes come off is something they disagree on, from January to mid-February onwards. What they agree on is the weather: late March into early April is one of the two windows they name, with rarely more than a brief shower and temperatures mild enough for driving the region or walking the beaches all day. Our row backs it at 24.6C over 13.1C with 38.1mm across 4.3 precipitation days. The summer school holidays are over. The record: 10 hours of sun, a 21.5C sea and AQI 20, the cleanest air here.

December here is warm, sunny and unlikely to be wet - our row gives 24.2C with 15.5mm across 2.8 precipitation days - but regulars call Christmas itself a lottery, with one year cold enough to send people shopping for jumpers and another over 43C for days on end. Our monthly average sits a long way under that upper figure. The reliable part is the calendar: Australian school holidays begin mid-December and run to the end of January, families rebook the same week year after year, and the stretch between Christmas and New Year is both the busiest and the dearest. If the dates are flexible, they say keep to early December. The sea is 20.2C, cool as ever here. The record: 11.9C nights, humidity 63 percent, 12.6 hours of sun and AQI 22.