Western Australia Surf Forecast by Craig Brokensha (issued Monday July 18th)

Best Days: Today, tomorrow, Sunday morning, Tuesday and Wednesday next week

Features of the Forecast (tl;dr)

• Inconsistent, long-period SW groundswell building tomorrow, peaking in the PM with mod-fresh E/NE tending lighter N/NE-NE winds
• Deteriorating surf Wed with strengthening N/NE tending N winds
• Large pulse of W swell Thu PM with strong to gale-force onshore winds, easing Fri with W-W/NW winds
• Strong W/NW tending SW winds Sat with a building windswell
• Large SW groundswell Sun with variable tending W/NW winds
• Easing surf Mon with N/NW tending W/SW winds
• XL SW groundswell Tue with variable NE tending NW winds
• Secondary pulse of SW groundswell Wed with similar winds

Recap

Friday's large, onshore surf cleaned up and eased back from a pumping 6-8ft across the South West, 3ft in Mandurah and 2-3ft across Perth, much smaller yesterday but still fun and to 3-4ft in the South West while Perth and Mandurah were back to 1-2ft.

Today is small but clean in the South West, while a new pulse of W'ly swell is offering 1-2ft waves across open beaches with light winds. Early onshore breezes have gone variable across Perth creating improving surf.

This week and weekend (Jul 19 - 24)

Our new, inconsistent W/SW groundswell due into tomorrow is on track, with it generated by a strong frontal progression firing up towards South Africa last week. It provided the pumping swell into the final two days of the WSL contest, with the progression weakening while pushing east of the South African continent late last week.

It'll be inconsistent but we should see the swell building all day and reaching 5-6ft across the South West with 1-2ft sets in Perth and Mandurah.

Winds will be best early but OK into the afternoon with moderate to fresh E/NE tending weaker (variable) N/NE-NE winds.

The swell will ease Wednesday as conditions deteriorate under a strengthening N/NE tending N winds ahead of an approaching trough, come low pressure system.

The swell generating potential off this trough/low has been downgraded with it only forming once pushing across us, though we're likely to see it 'bombing' once moving off our South Coast.

This will bring strengthening gale-force winds right across the south-west tip of the state on Thursday, bringing a rapid spike in localised stormy windswell but with terrible conditions.

The low will quickly track south-east while deepening, leaving weaker W'ly winds ahead of a secondary, stronger approaching frontal system. The chance for an early N/NE breeze in Perth looks minimal but we'll have a closer look at this on Wednesday.

Now, the secondary frontal system approaching through the end of the week will project a fetch of gale-force W/SW tending SW winds up and into us during the weekend, bringing stronger W/NW tending SW winds on Saturday and a large building groundswell that should peak Sunday to the 10ft+ range in the South West, 3-4ft across Mandurah and 3ft in Perth.

It looks like we'll see a high move in quickly from the west ahead of another front and this should bring a window of lighter winds across all locations and the peak in large, lumpy swell.

The next front will bring onshore winds into the afternoon out of the W/NW and with this we're looking at one of the larger swells this year for the region.

The initial stages of this next front will be a polar low, west of the Heard Island region, generating a fetch of gale to severe-gale W/SW winds, then projecting north-east while weakening a touch before restrengthening on approach to us.

The strengthening on approach to us will generate the largest size on Tuesday and it looks like we'll see winds go variable when it arrives. Surf to 15ft is due in the South West, 3-5ft across Mandurah and 3ft in Perth, with a reinforcing smaller pulse for Wednesday with light winds. More on this in the coming updates.