Gas Bay - surf spot statistics

Best Surf Season (March - May)

As autumn settles over the southwest coast, Gas Bay hits its stride. The Indian Ocean continues to churn out consistent, long-period groundswells from the SW quadrant, with average heights settling in the 1.9 to 2.3-metre range and periods stretching to 12.5–12.9 seconds. More importantly, the synoptic pattern shifts: a semi-permanent high-pressure ridge builds over the Great Australian Bight, funnelling a steady stream of offshore winds from the E to NE quadrant. With ideal wind frequencies climbing to 20–29%, you get clean, groomed faces peeling down the bay. This is the window for fun, rippable waves with the occasional pumping swell when a strong low spins up south of the continent.

Fair Surf Season (June - November)

Winter and spring deliver the biggest and most powerful swells of the year at Gas Bay. From June through August, average heights surge to 2.6–2.8 metres with periods of 13.0–13.3 seconds – true XL potential. Swell directions remain dominated by SW and WSW, wrapping beautifully into the bay. However, the wind regime becomes a double-edged sword. Frontal systems sweep across the Southern Ocean, bringing frequent onshore flows from the W and SW that can chop up the surface. Ideal offshore winds from the NE quadrant drop to 18–22% in winter and 15–18% in spring. You’ll need to pick your windows carefully, often early mornings before the sea breeze kicks in or during brief high-pressure interludes. When it lines up, expect very powerful, long period waves that demand respect.

Low Surf Season (December - February)

Summer is the quietest time at Gas Bay. Average swell heights dip to 1.8–1.9 metres, and periods shorten slightly to 11.8–11.9 seconds. While the swell direction is still predominantly SSW–SW – a favourable angle – the dominant wind pattern is the nemesis. A persistent surface trough and thermal gradients generate strong SE to SSE winds, which blow directly onshore or cross-onshore for this west-southwest-facing beach. Ideal offshore wind percentages bottom out at just 12–16%. The result is often choppy, messy conditions, though occasional fun-sized waves can be found if a southerly buster clears the air or a rare E wind sets in. For the dedicated surfer, it’s a time for grovel boards and low expectations.

July: The Deep Winter Peak

July delivers the largest average swell of the year at 2.8m with a 13.1s period. Swell from the SW and WSW dominates (34.5%), with 13.2% of the total exceeding 2.5m – these are massive, charging waves. The catch: onshore W and WSW winds reach 21.6%, often accompanying the same fronts that generate the swell. Ideal offshore winds slip to 21%. Patience and a sharp eye on the synoptic charts are required. When a transient high sets up over the Bight, the wind clocks to the NE, and Gas Bay turns into a heavy, pumping arena. The combination of XXL swell and offshore breeze is the stuff of legends, but it only occurs on a handful of days each month.