Western Australia Surf Forecast by Ben Matson (issued Tuesday 12th March)

Best Days: Protected spots Monday, Tuesday morning, Wednesday morning protected spots, Thursday morning

Recap: Small surf Saturday gave way to a large groundswell Sunday afternoon and Monday, that reached 8-10ft+ at exposed spots. A second, even larger S/SW groundswell has pushed across the coast today, generating epic surf across the lower SW, though there’s been a very large variation in size due to the extra southerly component in the swell direction. Based on surfcam footage, some of the reefs around Margaret River were pushing 12–15ft (see below, from our Margs surfcam) - with way bigger at offshore bombies - however Yallingup didn’t look much more than 6-8ft, and wave heights were very small throughout Mandurah and Perth (due to the shadowing offered by Cape Naturaliste and Rottnest Island). Winds were moderate to fresh SE this morning so conditions were clean, ahead of the afternoon sea breeze. What a day!

This week (Mar 13 - 15)

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*this week's Forecaster Notes will be occasionally brief and erratic, as Craig is on annual leave - they’ll be updated Tues/Thurs/Sun - to receive notification when they’re updated, please update your account preferences*

We’re looking at steadily easing swells from today into Wednesday, though a front that’s developing cut-off low SW of the state will reinforce energy into the afternoon and Wednesday, in addition to some small groundswell generated by ex-TC Haleh.

I haven’t been able to hindmost the specifics of this latter system but Craig’s notes (on Friday) indicated there’d be a mix of swells in the 4-6ft range for Thursday, and Wednesday should be of a similar size, perhaps the odd bigger set leftover from today. Seems about right based on a quick scan of the data.

Wave heights will then ease back into Friday.

The key difference for the next few days is that these mid-week swells should provide a little more size across Perth and Mandurah coasts thanks to a better swell direction (more south-west than south). However we’re still talking pretty small surf in general, just a couple of feet at best.

And as for local winds, Mandurah and Perth are at risk of fresh southerly winds on Wednesday and Thursday thanks to a high pressure system W/SW of the region, extending a ridge into the coast.

Ironically, the cut-off low passing south of WA on Wednesday will create a weaker pressure gradient across the lower SW, so local winds should be light to moderate S/SE early, tending SW throughout the day, and persisting of this nature into Thursday - so we’ll see the best conditions over the next few days in the south (which is the opposite of the norm).

Better winds are expected on Friday as the high pressure ridge weakens with the approach of another front.

This weekend (Mar 16 - 17)

A strong polar low and associated broad Southern Ocean front will move through our swell window all week originating from way over near Madagascar, generating a large swell that’s due to arrive on Saturday, building slowly at first ahead of a more rapid increase into Sunday where we’ll see a peak. 

The raw data for this swell looks similar to today’s event, but it’s a completely different kind of swell, from a different kind of weather system, in a different part of the swell window. As such I don’t think we’ll see quite as much size as today, but the Margs region should peak in and around the 10ft+ mark on Sunday. Expect significantly smaller surf on Saturday ahead of the building trend.

This swell will be much better positioned for Mandurah and Perth too, where we should see wave heights peaking around 3-4ft+ and 2-3ft+ on Sunday (again, smaller Saturday).

The concern this weekend will be a strengthening ridge across the coast, between an Indian Ocean high and an inland trough of low pressure. This will maintain fresh S/SE winds across all coasts, and will confine the best waves to sheltered locations. I’ll revise this in Thursday’s update. 

Next week (Mar 18 onwards)

A steady stream of strong fronts through the Southern Indian Ocean look like they’ll maintain a healthy ongoing trend of swell for the region into the long term, with a couple of large embedded pulses in the mix too. Certainly looks like a very active period ahead for WA surfers. 

More on this on Thursday.