One of Margaret River’s greatest strengths is something most visitors don’t notice: the balance between warm days and cool nights. This balance, known as diurnal range, plays a huge role in shaping the region’s elegant wine style.
What is diurnal range?
Diurnal range is the difference between the warmest part of the day and the coolest part of the night. In regions with a large diurnal range (like inland valleys or high-altitude sites), hot days are followed by very cold nights. In coastal areas like Margaret River, the ocean acts like a natural air-conditioner, moderating temperatures so the day-to-night difference is much smaller.
Why it matters for wine?
Vines make sugars during the day through photosynthesis and burn some of them off at night through respiration. A smaller diurnal range means grapes ripen steadily: flavours and sugars build up during the day, while cooler nights protect delicate aromas, acidity, and tannins. The result is wines with freshness, balance, and finesse.
Margaret River’s advantage
The region’s average day-to-night difference during the growing season is around 10°C — low by global standards. Warm (but rarely scorching) days and dependable sea breezes keep vine leaves in the photosynthesis “sweet spot,” while nights stay mild enough to preserve natural acidity and aromatics. This even, gentle climate underpins Margaret River’s world-class reputation.
What this means in the glass?
- Chardonnay: Bold flavours balanced by crisp acidity, delivering the signature Margaret River style of power with precision.
- Sauvignon Blanc & Semillon: Retain their vibrant freshness and lifted aromatics, even without icy nights.
- Cabernet Sauvignon: Long, even ripening ensures tannins mature fully without sugar levels racing ahead, producing wines of elegance, cassis-led fruit, and fine tannins.
- Shiraz: Moderate warmth and sea breezes favour spicy, medium-bodied styles with red and blue fruit, fresh acidity, and supple tannins.
The takeaway
Margaret River may produce just 2% of Australia’s wine grapes, but its climate advantage is profound. The region’s night-and-day balance gives winemakers the ability to craft wines that are consistently vibrant, fresh, and refined. It’s one of the quiet secrets behind Margaret River’s global reputation for excellence.
This article is courtesy of Margaret River Wine Association.