Western Australia Surf Forecast by Craig Brokensha (issued Monday 12th August)

Best Days: Wednesday morning protected spots in the South West and Mandurah, Thursday all coasts (dawn Margs), Saturday protected spots, dawn Sunday

Recap

Great conditions with fun waves across the beaches and magnets in the South West on Saturday, tiny and clean to the north. The swell bottomed out into yesterday, but today we've seen a new W/SW groundswell fill in, with clean conditions early across all locations, more N'ly this afternoon.

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This week and weekend (Aug 13 - 18)

We've got a tricky week of conditions and swell ahead as surface troughs move through, bringing winds from all degrees of the compass.

Today's kick in W/SW swell is due to ease, but a larger W/SW groundswell is due into the afternoon, peaking Wednesday, though the size of this has been downgraded a little further from Friday.

The low linked to the swell didn't end up being as strong or as favourable as forecast on Friday but we should still see Margs coming in around 8ft+ when the swells peaks through Wednesday, 3ft on the sets in Mandurah and 2-3ft in Perth.

Winds tomorrow will be poor and shifting from a pre-dawn W/NW to W/SW through the early morning.

Wednesday will offer a window of cleaner conditions as a trough moves in, bringing strong S/SE winds across the South West, best in protected spots while Mandurah and Perth look onshore at dawn with S/SW breezes, shifting S/SE through the morning (possibly S/SW all day in Perth).

Thursday looks better in Perth and Mandurah with E/SE offshores as the swell eases. Margs is likely to see early variable winds, though shifting quickly to the W/NW after sunrise.

Sets to 6-8ft are likely in the South West, 2-3ft Mandurah and 2ft+ Perth.

Moving into Friday a strengthening mid-latitude frontal progression will bring strengthening NW winds ahead of a late W/SW change and a mix of building windswell and mid-period swell, peaking through the weekend.

The mid-period swell will be generated by a broad but relatively weak fetch of strong to gale-force W/SW winds being projected through our swell window this week, with the size coming in around 8ft in the South West, 3ft Mandurah and Perth.

Winds look to swing around to the S/SE again as a trough moves through Friday evening, NE tending N/NE on Sunday as a new S/SW groundswell fills in.

The source of the S/SW groundswell will be the tail of the frontal progression, with a fetch of gale-force S/SW winds forecast to be projected through our southern swell window. The swell should fill in Sunday, keeping the South West around 8ft on the sets, 2-3ft Mandurah and 2ft+ Perth with that northerly breeze.

Winds will go N/NW-NW on Monday as the swell eases and from here we're in for a run of large onshore surf with W-NW winds through all of next week and weekend. This will be linked to significant frontal progression setting up through the Southern Ocean under the influence of a strengthen node of the Long Wave Trough forming in the Indian Ocean and pushing east. More on this Wednesday though.