Western Australian Forecast by Craig Brokensha (issued Monday December 23rd)

Best Days: Protected spots Thursday morning, Friday morning for the keen, Saturday morning in the South West

Features of the Forecast (tl;dr)

• Strong S/SE winds tomorrow with a late increase in W/SW swell
• Large mix of W/SW swells Wed with early S tending strong S/SW winds (S/SE early to the north)
• Mix of easing W/SW swell and new mid-period SW swell Thu AM with fresh S/SE tending strong S/SW winds
• Easing surf Fri with early S/SE-SE tending strong S/SW winds
• Small early Sat ahead of a new SW groundswell for the PM
• E/SE tending strong S/SW winds Sat 
• Easing swell Sun with fresh S/SE tending strong S/SW winds

Recap

The surf dropped away into Saturday with less favourable winds across all locations, while our new long-period W/SW groundswell for yesterday provided better 6ft surf across the South West with fun, small waves to the north as winds shifted back more offshore but with strength.

Today the swell is on the ease but conditions are still great with a lighter offshore wind.

This week and weekend (Dec 24 - 29)

This coming week revolves around the large W/SW groundswell and mid-period energy due to arrive on dark tomorrow but peak through Wednesday.

The swell has been produced since last week with an initial strong low to the south of South Africa generating a fetch of severe-gales before slowly weakening over the weekend while projecting east and expanding in scope.

This will result in a long-range, inconsistent W/SW groundswell mixed in with more consistent, slightly smaller mid-period swell.

Size wise the South West should come in at 8ft to occasionally 10ft on the exposed reefs with 2-3ft waves in Mandurah, 2ft+ across Perth but early S’th winds will quickly shift strong S/SW creating generally poor to average conditions. Perth and Mandurah should see early S/SE winds but again, best towards southern corners.

Thursday will see the swell starting to ease, though a frontal system pushing up and into us will bring with it some moderate + sized, reinforcing energy. The South West should ease back from 6-8ft on the sets across the magnets, 2ft to occasionally 3ft in Mandurah and 2ft in Perth.

Winds will shift S/SE and ease a little across the state Thursday though remain fresh and strengthen into the afternoon while tending S/SW.

Friday is still looking dicey wind wise but we might see an early S/SE-SE breeze across the South West, fresher S/SE-SE to the north as the size backs off further.

The weekend will start off clean but smaller with tiny waves across Perth/Mandurah and surf in the 3-5ft range across the South West.

Into the afternoon, some new moderate sized SW groundswell is due to arrive, generated off a pre-frontal fetch of off-axis gale-force NW winds around a deepening polar low tomorrow.

No major size is expected with the South West due to perform best, building back to 4-5ft with tiny waves to the north.

Sunday looks similar in size but with unfavourable S/SE tending stronger S/SW winds.

Longer term, moderate levels of mid-period swell are due into next week with improving winds from Tuesday, but more on this Wednesday.